Читать книгу Jeep Wrangler YJ 1987-1995 - Don Alexander - Страница 8

CHAPTER 2

TIRES AND WHEELS

Tires play a critical role for off-road performance. Striking a compromise between good highway handling and traction in all four-wheeling conditions is tricky. Choosing tires has become trickier for stock YJ replacements, as the market has changed and the choices are limited in the smaller sizes. But if you go more extreme, there are many choices, such as the Nexen Roadian MTX mud-terrain tire mounted on Raceline Monster beadlock wheels.

In 1987, the Wrangler YJ was introduced with 29-inch-diameter tires. At that time, 31-inch-diameter tires were large. When the YJ Renegade went on sale, it used 30-inch-diameter tires. Today, with moderate lifts, 35-inch tires are common on YJ builds. To run even a 31-inch-diameter tire requires about a 2.5-inch lift. Going up to 33-inch tires takes a 4-inch lift, and 35-inch tires require a 5-inch-plus lift. Tire diameters up to 40 inches are possible but require more clearance. We will explore lifts in the suspension chapter.

Mud-terrain tires, such as the Falken WildPeak mud-terrain tire (left), are generally preferred for serious off-road Wranglers. They are especially good on soft surfaces where the large tread blocks and softer rubber compound increase grip. They also look more aggressive. All-terrain tires, such as the BFGoodrich All-Terrain T/A tire (middle), appeal to more casual off-road use due to better wear and a quieter ride on the highway. While the AT tire may have a harder rubber compound, the increased tread area due to a smaller void ratio allows most all-terrain tires to perform with the equivalent mud-terrain tire in most off-road conditions. The Mickey Thompson Baja ATZ P3 (right) all-terrain tire blurs the line between mud- and all-terrain tires. More of a hybrid, the ATZ P3 features large tread blocks, a smaller void ratio, numerous sipes in the tread blocks, and a rubber compound softer than a typical all-terrain tire but harder than a mud-terrain tire. Many tires companies have introduced this style of hybrid all-terrain tire. This new category is often called extreme all-terrain.

Stock Replacement Tires

The stock wheels and tires on the Wrangler YJ are very small by today’s standards. The 15-inch, 6.5-inch-wide wheels allow few off-road tire choices. The 16-inch-diameter wheels offer more choices, but a maximum width of 7 inches restricts the selection. The 7-inch-wide rim of the stock YJ can handle up to about a 30-inch-tall tire on the stock setup for light-duty off-road driving. An increase in tire diameter requires a lift and more suitable wheels for the application.

Off-Road Tires

Most Wrangler YJ owners either purchase a used modified rig or plan to modify the Wrangler for capable off-road experiences. Larger tires are the current norm; 33-inch-diameter tires are on the small end of the spectrum. To use 33-inch-tall tires requires at least a 4-inch lift, while a 35-inch tire will need more than 5 inches of lift. Many YJs run 37-inch tires, and more extreme builds use up to 40-inch tires. Both require extensive modifications, usually a stretched wheelbase and the use of coilover springs and shocks.

Tires are the most-common performance modification to Jeep Wranglers. All-terrain and mud-terrain tires offer more aggressive looks and much-improved performance when you wheel off-road. But there is a downside.

All- and mud-terrain tires use a softer rubber compound, even softer on the mud terrains. This accelerates tire wear and increases rolling resistance due to softer tread compounds, so fuel economy takes a hit. The more aggressive tread designs of all- and mud-terrain tires increases road noise. This is most notable on mud-terrain tires. The larger tread blocks on a mud tire also increase tire squirm on the highway, which reduces handling responsiveness.

To have a good selection of off-road tires requires an upgrade to a larger, wider wheel. Taller tires will require a suspension lift for clearance. This improves off-road performance drastically. And the more-aggressive look of the all-terrain and especially the mud-terrain tires are an integral element of the Jeep persona.

All-Terrain Versus Mud-Terrain Tires

Which is better, an all-terrain or a mud-terrain tire? Which side of the fence are you on? While there has never been a clear winner in this argument, there are many factors to take into account: highway versus off-road miles, weather conditions, terrain, and road surface are just a few. But with the launch of a new off-road tire category, called by some the rugged terrain (RT) or extreme all-terrain, the line between all-terrain and mud-terrain is blurred. These new-generation all-terrain or RT tires offer more aggressive tread patterns and sidewalls while retaining a smaller void ratio for reduced noise on the highway and harder rubber compounds for better tire wear.

Tread Design Differences

The most obvious difference between the all-terrain and mud-terrain tire lies in the tread design. A mud-terrain tire has more aggressive tread blocks and a larger void ratio. The void ratio is the percentage of the total tread block area versus the area of the total tire tread. The tread blocks on a mud-terrain tend to be larger and thicker than an all-terrain tire.

The thin slits in the tread, called sipes, allow the tread to flex and the edges to better grip hard surfaces such as rocks. Sipes are used in both all-terrain and mud-terrain tires. Generally, an all-terrain tire will have more sipes, which improves grip on hard surfaces. The new, more-aggressive all-terrain tires create as much or possibly slightly more grip than the same size mud-terrain tire.

While a good mud-terrain tread design can keep rocks from lodging between tread blocks, the design must also eject mud and snow. Some designs do this more efficiently than others. In general, the larger void ratio of the mud-terrain is better in soft surface conditions, but the tread blocks need to flex to eject snow and dense mud.

Tread design plays a role but so does tire pressure. Lower tire pressure helps when the voids become filled with debris, ice, snow, or heavy mud. And some all-terrain tread designs are better in snow but lack the ability to keep small stones out of the tread voids.

Sidewall Design

One of the most important elements of tire design is the structure of the sidewall. When four-wheeling on rocks, in ruts, or on side slopes, it can be critical for the sidewall tread to have good grip. A lack of grip means the tire can slide sideways off the edge of a rock, the slope on a side hill, or within a series of ruts. Slipping can alter your desired path or cause you to bang a rock slider, skid plate, or bumper on a rock that you thought you could avoid.

The tire sidewall needs to be able to flex to conform to the road surface and to have a design that allows rocks and snow to be ejected from the tread pattern. Most off-road tires do a better job of keeping tread voids cleared when aired down (tire pressure lowered to a lower pressure).

An additional factor affecting off-road tire performance relates to the cord angles in the sidewalls. A small change in cord angles can affect the sidewall stiffness. While this is a factor on all Jeep models, it becomes more critical on lightweight Jeeps such as the Wrangle YJ. If the sidewall is stiffer, the tire must be aired down to a lower pressure to achieve the same spread of the tire contact patch.

The void ratio is the area of tread blocks versus the area of the gaps between the tread blocks (white in the illustration). All-terrain tires use a small void ratio, meaning more rubber is on the ground. Mud-terrain tires use much larger void ratios, meaning less rubber is on the ground but there is more ability for the tire to grip a surface, especially soft surfaces such as mud, sand, and snow. Larger void ratios also create more noise on the highway.

The weight of the vehicle, or more specifically the weight resting on each tire contact patch, is also a factor. Where one tire may achieve the ideal tire contact patch spread at 14 psi on a YJ, another tire may need to be aired down to 10 psi for the same result. A pressure of 10 psi is marginal for a non-beadlock wheel. We have aired down Wrangler JKs weighing more than 6,000 pounds to about 5 psi with beadlocks to achieve ideal pressures for snow, mud, sand, and icy conditions. The sidewalls on those tires were very stiff. To get the same contact patch spread on a 3,500-pound YJ may require airing down to about 3 psi.

Rubber Compound and Wear

All-terrain tires tend to have harder rubber compounds than mud-terrain tires, so the mud tire will wear more quickly with everything else being equal. Even though the all-terrain is harder, it has more rubber on the road or trail surface due to a smaller void ratio. This usually means the all-terrain tire will have slightly better traction on hard surfaces given equal tire sizes. The mud-terrain will grip better on soft surfaces. This is best distinguished when the tire is operating “in” a surface as opposed to “on” a surface. Think “in” sand, mud, snow, and soft, loose dirt versus “on” asphalt, ice, or hard-packed dirt.

Top left: The BFGoodrich All-Terrain T/A KO2 tire has one of the more aggressive sidewall designs. The siping allows flex for better grip. The ridges between the sidewall tread blocks are stepped to help eject rocks and debris from the sidewall. Top right: The Mickey Thompson Baja ATZ P3 all-terrain tire has a sidewall design more like a mud-terrain tire. This sidewall design grips very well on rock edges and the sides of ruts where little or no tread is gripping the surface. Bottom left: The Falken WildPeak AT03 has a very aggressive sidewall for an all-terrain tire. The stepped ridges on the upper part of the sidewall progressively grip the edges of rocks and slopes for better grip. They also dig into soft surfaces for even more bite. Bottom right: This all-terrain tire, the Nexen Roadian AT, has a conservative sidewall design, but the triangular-shaped scallops on the lower portion of the sidewall provide a surprising amount of grip on loose dirt and large, sloped rocks.

Types of Off-Road Surfaces

When off-road, the advantages of the all-terrain versus the mud-terrain tires is less clear. In some conditions, the mud-terrain tire provides a slight advantage. But the differences are minor. The big issue is the type of surface.

Exceptional tire compliance allows for much easier rock crawling by sticking to a slanted rock. This rock has a 60-degree slope. Most of the tread is in contact and the sidewall is contributing some grip as well.

Hard Surfaces

For the most part, the all-terrain tires are better on hard surfaces. While the rubber compound is a little harder, the void ratio is smaller, meaning there is more rubber on the ground for equal-size tires at similar pressures. The advantage diminishes when the surfaces are wet.

For hard dirt or rocky dirt surfaces, the difference between mud- and all-terrain tires is very small. For sand or soft, loose dirt, mud-terrain tires will give better traction. For wet dirt and mud, a mud-terrain tire is best.

Soft Surfaces

Due to deeper, larger tread blocks, the mud-terrain tires perform at their best in soft surfaces. Mud, sand, loose dirt, and snow are conditions giving the mud-terrain tire better performance. In certain types of snow, especially in slushy, sticky snow conditions, the mud-terrain has an advantage only if the tread design (and lower tire pressures) are able to eject the snow from the tread voids. ■

Tire sidewall construction plays a major role in determining how well a tire conforms to the surface. Even though the Nexen Roadian MTX mud-terrain tire features an F load range (meaning the sidewalls are very puncture resistant), the sidewall ply angles allow for a very flexible tire. This 37-inch tire is at 14 psi on a 17-inch beadlock wheel. Most tires would need a pressure of 10 psi or lower to enjoy this much tire deformation on the rocks. At 14 psi, the Nexen does need to be on a beadlock wheel. Keep in mind that most newer mud- and all-terrain tire designs are intended for heavier rigs similar to the Wrangler JK. The lighter YJ would need to run a much lower pressure to allow good tire conformity. On most current mud-terrain tires, pressures well below 10 psi would be needed, which means investing in beadlock wheels.

Tire Size, Diameters, and Ground Clearance

Increasing tire diameter allows more ground clearance and larger contact patches on the ground. Keep in mind that the low points under any Wrangler YJ are the center sections of the axle housings and the leaf spring perches for non-leaf-over spring (stock) suspensions. Spring under lifts raise the chassis/body but not the axle housing. A suspension lift is installed mostly to gain clearance for larger-diameter tires. So going from the stock 29-inch tire in the YJ to a 33-inch-diameter tire will increase ground clearance by 2 inches.

Increasing tire sizes increases tire weight. Off-road tires weigh a lot. The tread is the heaviest part of the tire and it is farthest from the center of rotation, which means all the weight when rotating (called rotational inertia) creates very large loads on ball joints, tie-rod ends, and suspension components. The inertia caused by weight away from the center of rotation increases as rotational speed (RPM) increases, as the distance from the centerline increases, as well as when the tire weight increases.

Worn steering components lead to shimmy and death wobble on the solid axle of a YJ. Increasing tire size requires upgrading key steering components to ensure performance and safe operation. Additionally, as tire size goes up, it is crucial to have tires dynamically balanced (see the wheel/tire balancing section later in this chapter) to reduce the possibility of shimmy or wobble.

Advantages and Disadvantages

On the highway, all-terrain tires offer better handling and steering feel. Mud-terrain tires have more squirm due to larger tread blocks. As for road noise, all-terrain tires are quieter; so are the new generation of extreme all-terrain tires (RT).

If the surface is loose sand, gravel, or small rocks, the mud-terrain tires are best. All-terrain tires are better on harder surfaces. In rain, snow, and ice, all-terrain tires have an advantage with some mud-terrain tires being better in some types of snow.

For rock crawling, it is a toss-up. The tread design and ply angles will make a difference for both all-terrain and mud-terrain tires.

Tire Size and Off-Road Performance

Larger-diameter and wider–tread width tires have a larger rubber contact patch on the ground, especially at low tire pressures. This improves traction. Since taller tire sidewalls can be aired down with a greater reduction in sidewall height, ride quality is better. The downside of larger tires is increased brake and steering system wear. Fuel economy also takes a negative hit.

Sipes are the thin cuts in the tread blocks. They allow the tread blocks to flex and provide additional edges to help grip the surface. They are most effective on hard surfaces such as rocks and ice. The tire on the left has considerable siping. Siping is limited on the tread design of the tire on the right. Notice the small ridges in the tread between the tread blocks. These ridges help eject rocks and other debris from between the tread blocks.

Sidewall lettering can provide a wealth of information. This Falken WildPeak AT03 has a load range E rating. This is the equivalent to a 10-ply tire. The load range and sidewall design of this tire make it very durable against punctures.

The Nexen Roadian MTX uses a moderately stiff sidewall. The sidewall has good flex. The tire pressure is 12 psi. Grip is good, allowing the tire to comply with the terrain, which improves traction.

Tire Compliance Over Rocks and Obstacles

If you plan to use your YJ for serious rock crawling or steep hill climbs and descents, especially with big ruts, then tire compliance of the tread over road surface irregularities is extremely important. Tire compliance is the ability of the tire tread and sidewall to conform to the shape of rocks, road surface irregularities, or other obstacles. Both sidewall stiffness and tread design are factors. Tire pressures are key, but tire design plays a factor in how low a pressure you can run, especially without beadlock wheels (see the wheel section for an explanation of beadlock wheels).

Tread Block and Sidewall Design for Off-Road Performance

Tread block design is a critical factor for traction in all off-road conditions. Some tread block designs work more effectively in some conditions, such as hard surfaces and rocks, while others perform better on soft surfaces of sand, mud, and snow. Soft surfaces require more forward grip for braking and acceleration, while hard surfaces need forward grip but also need lateral grip or side bite.

Lateral grip is where sidewall design is really important. Sidewall tread patterns can help hold the vehicle on side slopes and the sides of rocks. This is important in rock crawling and in heavily rutted trail sections where only the sidewall of a tire may be gripping the side of a rock, rut, or bank.

Sidewall grip plays a critical role in off-road driving situations, especially in extreme rock crawling. Without adequate sidewall grip, tires can slide off rocks and side slopes often, causing the vehicle to become stuck or worse. The Nexen Roadian MTX mud-terrain tires feature a unique sidewall tread pattern that is different from side to side. Both designs offer great grip.

Siping

Sipes are thin cuts in the tread of a tire. They allow the tire tread to separate slightly, which improves traction on ice and snow. For off-road use, the siping can improve traction when rock crawling. Depending on the siping pattern, they can also increase lateral grip, helping to hold the tire sideways on rocks, side slopes, and ruts.

Lateral Grooves and Crosscuts

Lateral grooves and crosscuts are similar to siping, but they are larger. This allows tread blocks to flex and grip soft surfaces and uneven terrain more effectively. At lower tire pressures, grooves and crosscuts can flex to help expel snow from the tread voids for better traction.

Forward and Side Grip

Tread and sidewall design play a major role in how a tire grips in low-traction situations. Good forward traction is critical for climbing and descending large rocks and hills. Side traction is crucial for holding on to side slopes, ruts, bumps, and rocks. Tire designs are a compromise. Different designs are better in certain off-road situations.

The Milestar Patagonia M/T tire is available in a wide range of sizes from 31-inch diameter in a 15-inch wheel and a 16x32-inch size that will work on the YJ with a slight lift.

The Milestar Patagonia M/T tire features an aggressive sidewall design and unique tread pattern with a fairly low void ratio for an mud-terrain tire.

Nexen Tire is new to the off-road market with both an all-terrain and the Roadian MTX mud-terrain tire. We spent five days comparison testing the Roadian MTX about a year before the tire was available to the public, and we were very impressed with all aspects of its performance.

The Nexen Roadian MTX features a more traditional mud-terrain tread design with effective siping and stone ejectors. Snow was the only condition we were unable to test in with this tire. It was great in sand, on the rocks, and on climbs and descents.

Tire Cutting, Slashing, and Ply Ratings

Cutting or puncturing a tire tread or slashing a sidewall is a fairly common occurrence off-road. Areas with sharp rocks are the most likely to cause problems. Two factors will help reduce the possibility of serious tire damage: running only load range D or E tires and airing down to a lower tire pressure.

Load range refers to the ply rating. Old bias-ply tires had a ply rating of up to 10 ply for light truck and off-road tires. With modern materials, fewer plys are needed to achieve the same strength and puncture resistance. A D rating is the equivalent of an 8-ply bias tire. An E rating is the equivalent of a 10-ply bias tire. Tires with D and E ratings provide the best protection off-road.

The BFGoodrich Mud-Terrain T/A KM2 is the latest in a long line of BFGoodrich mud-terrain tires. Every new version exceeds the capability of the last. This tire shines in the rocks and any soft surface. Tread wear and road noise are pretty typical of most mud-terrain tires.

The Maxxis Trepador Competition mud-terrain tire is very capable in extreme conditions. This tire is heavy and noisy on the highway but offers great performance in severe conditions and rock crawling situations. The tread and sidewall are very aggressive with deep tread blocks and a large void ratio.

The latest mud-terrain tire offering from Maxxis is the Razr. Featuring a new tread compound and tread block design, the Razr is designed to improve on-road performance and reduce noise while retaining great off-road traction and durability in all types of terrain.

For those with stock or slightly modified Wrangler YJs, the Maxxis Bighorn MT-762 is offered in several 15- and 16-inch-diameter wheel sizes as small as 29 inches tall.

The very aggressive Maxxis Creepy Crawler offers a high level of off-road traction in slippery conditions and in the big rocks while being DOT legal for highway use.

The Pro Comp Xtreme MT2 is another mud-terrain tire available in a wide range of sizes to accommodate mild to extreme YJ builds.

The Falken Wildpeak M/T features a stiff sidewall construction. This tire needs to be aired down more to achieve the same tire contact spread as a softer sidewall tire. At the top, the tire pressure is 28 psi and in the middle the pressure is about 12 psi, which is about the lowest advisable for non-beadlock wheels. The lower the tire is aired down (to 6 psi), the more effectively the tire conforms to the rock. This series of photos was taken on a much heavier Jeep. A lighter YJ would need even lower tire pressures for good contact patch compliance.

Tire Pressures for Jeep Wrangler YJ Off-Road

There are four important reasons to air down tires. First is to increase traction by increasing tire contact patch area. A 285 70-17 10-ply tire with inflation pressures reduced from 50 psi to 7 psi will increase the tire contact patch by up to 220 percent.

Second, aired down tires improve ride comfort. There is a significant difference.

Third is to reduce the chance of a sidewall puncture. Think of a highly inflated balloon. If you poke at it, it will likely puncture. A softly inflated balloon, when poked, has considerably more give and is not likely to puncture.

Fourth, aired down tires reduce damage to the road surface by spreading the weight over a greater tire contact patch surface area. This helps reduce erosion over time.

There are also some disadvantages, including reduced ground clearance due to a shorter sidewall from less pressure, increased possibility of the tire bead unseating from the wheel rim, and the need to air back to recommended highway tire pressures for your vehicle. For hard surfaces and rock crawling, higher pressures are needed to help keep the tire bead seated on the wheel rim and to protect the sidewall and tire bead from bottoming on the rim, which would likely damage the tire or even bend the wheel rim.

Airing down tires to a lower pressure allows the tire to conform to the terrain, increasing traction. This is very important for rock crawling for both climbing and descending. This tire is at about 15 psi and the tire contact patch and the sidewalls conform to the rock edge, allowing a much easier climb up the rock. With this Raceline Monster beadlock wheel, we have aired down as low as 4 psi on soft surfaces such as sand and snow.

Tire Deflator Types

Tire deflators are the easiest way to air down tires when you hit the trails. In general, there are three types of deflators.

The first type are tire pressure gauges that have a release valve for letting air out of a tire. These are very slow and require constant attention.

The second type are deflators that screw onto the valve stem and depress the spring-loaded valve core. These are adjustable for minimum pressure when they shut off. They usually come in sets of two or four. They are not much faster than a pressure gauge, but with four and automatic shut off, you can screw them on and walk away.

Wheelspin is always an issue when climbing steep rock ledges. The BFGoodrich Mud-Terrain T/A KM2 features a fairly stiff sidewall construction. Combined with the light weight of the YJ, this tire could have benefited from a lower tire pressure when airing down. The reduction in ground clearance from a lower tire pressure is not an issue, at least in this spot.

The Currie deflator removes the valve core from the valve stem, which allows rapid deflation. The gauge allows precise pressure monitoring. The deflator consists of a gauge, a plunger that unscrews the valve core, a fitting that screws onto the valve stem, and a pressure release valve. While the operator is a little more involved in the process, this is the fastest way to air down four tires—even faster than the set of four screw-on deflators. The cost is about half.

The valve core is spring loaded, so when the valve is depressed, air can flow in under pressure or out to air down. The airflow is very restricted by the valve core. The Currie deflator removes the core but captures it within the housing for easy replacement.

To use the Currie deflator, screw the fitting onto the valve stem, depress the plunger and rotate until it captures the valve core, unscrew the valve core, and pull the plunger out. Open the air valve to deflate, close the air valve to check pressure. When the desired pressure is reached, keep the valve closed, push in the plunger, and screw in the valve core until snug. Then, pull the plunger out so that the valve core cannot be unscrewed while unscrewing the fitting from the valve stem. Our project YJ weighs in at about 4,000 pounds. To get good tire contact patch spread on the fairly soft sidewall Nexen Roadian MTX tires, we aired down to about 6 psi. Beadlocks are a necessity at these low tire pressures.

This is a Mil-Spec Multi Choice Deflator from Extreme Outback Products. This high-quality deflator features detents from 20 psi down to 10 psi in 2-psi increments. It adjusts by rotating the knob on the top.

The Staun Tyre Deflators allow all four tires to be aired down at once. They are made from brass and have an adjustable pressure relief valve. They screw onto the valve stem.

The third type of deflator also screws onto the valve stem, but it also unscrews the valve core from the stem while capturing it within the nozzle. This type has a pressure gauge and on-off pressure relief valve for accurate control of tire pressure. This allows for very rapid airing down. One of these deflators is typically faster than four of the others. The downside is the need to watch the pressure as it drops.

Rock Smasher Engineering has a hybrid system called 2Way Air that uses a system of tubes plumbed into the vehicle. The tubes run to Schrader valves at each corner and to a shut-off valve. There is also a pressure relief valve that is adjustable to control pressure when airing up. Tube “whips” are placed from the chassis mounted valves to the tire valve stems. The system can be used with a compressor or a Power Tank. This system works for airing down and up. ■

A portable air compressor, such as the Viair compressor, provides an easy, compact way to air tires back up for the highway. This economic alternative is somewhat slower than the twin compressor with air tank system.

The Power Tank regulator shows the remaining CO2 volume and can be adjusted for filling tires or running air tools.

A quick and convenient way to air up features the compressed CO2 tank and regulator system from Power Tank. This high-pressure system fills large tires very quickly. The tanks come in three sizes: 15, 10, and 5 pounds. The tanks do need refilling. With our 15-pound Power Tank, we can inflate our 37x12.50x17 tires (all four) from 10 psi to 26 psi in about 2.5 minutes. We can fill about 32 tires this way.

The Power Tank inflation time chart shows the time needed to air up different sizes of tires to a variety of tire pressures.

Wheels

Wheels for performance vehicles tend to be lightweight. While weight is an important factor for off-roading, strength and durability are more important. Wheels for the YJ need to fit the desired use and the modifications being made.

The stock YJ wheels are small and limit tire choices. They feature the same bolt pattern as the newer TJ with five lugs on a 4.5-inch bolt pattern. There are many wheels available with this bolt pattern in a variety of widths and diameters. Wheel adapters can also be used to change the bolt pattern to a 5-on-5 pattern (five bolts on a 5-inch circle). Or if you upgrade to heavy-duty axle assemblies, such as a Currie RockJock 60 or 70, then the bolt circle will need to be larger, such as five bolts on a 5.5-inch circle to accommodate larger hubs.

Wheels for the Wrangler YJ come in steel and alloy aluminum. Both materials are used on standard bead rims or beadlock versions.

Alloy Versus Steel

Each material used in the manufacturing of wheels offers advantages. Steel is less expensive, strong, and malleable, meaning that the wheel will bend on impact, not crack or break. A bent steel wheel can be hammered back (though with great difficulty) into a reasonable shape to hold air if deformed on the trail. A cracked or broken alloy wheel cannot be repaired. Any wheel can be scratched, gouged, or more severely damaged when off-roading.

Alloy wheels are lighter for the same size and strength. They also offer an extensive range of styles. Aluminum alloy also dissipates heat better than steel, helping to cool brakes under extreme conditions. They are also more costly.

Alloy wheels are manufactured using four different processes: forging, high-pressure die-casting, low-pressure die-casting, and gravity casting. Forged wheels are the toughest and strongest, but they are also much more expensive (as much as double the cost). Many forged wheels are not street legal and are mostly used for competition.

Cast wheels are by far the most common. The casting process is less important than the quality of the materials used in the process. Though rare, cast wheels can crack or even break from hard impacts off-road.

Standard Bead Versus Beadlocks

Modern wheels and tires are manufactured to very close tolerances, so wheel bead diameters are a very close fit to the tire bead. For this reason, most Jeep owners can use a standard bead wheel (such as the stock wheel on a JK).

There is also a category of wheels known as beadlock-style wheels. These look like beadlocks but have a standard wheel bead. A true beadlock wheel has an outer ring that bolts to the wheel. The ring holds the tire bead in place so that it cannot become dislodged from the wheel at low pressures in extreme conditions.

We have tested many different tires on standard rims down to 10 psi for soft surface, low-speed four-wheeling. This is usually a low enough pressure for adequate traction. More extreme situations, such as deep snow or wet, muddy, or snow-covered rocks, require lower pressures as do tires with a very stiff sidewall. Here is where beadlocks are necessary. We have tested beadlocks at tire pressures as low as 3 psi in snow, on soft surfaces such as sand and mud, and on snowy, muddy rocks on black diamond trails.

Alloy beadlock wheels are very expensive. Steel beadlocks are more economical. Several companies make beadlock kits for steel wheels. They consist of a ring that is welded to the wheel and has a matching outer bolt-on ring. Rockstomper and Riot FabWorks both offer weld-on beadlock kits. Welding the beadlock ring to the wheel requires good welding skills.

These steel beadlock wheels look like homemade modifications on standard steel wheels. The beadlock ring uses only 16 bolts to hold it in place. Most beadlocks use 32 bolts. This wheel is not well maintained, as shown by the rust. With only 8 bolts, balancing may be issue. Beadlock wheels can be dangerous. It is important to use quality materials that are properly engineered. A home-built beadlock is not a sound idea. And it is important to check the torque every 30 to 60 days to ensure the beadlock ring is secure.

There are a few myths about beadlocks. The most significant is that beadlocks are not street legal. That is not true, though most manufacturers make the claim that their beadlock wheels are not “recommended” for highway use. This is generally because the manufacturer has not had the beadlock wheels tested to Department of Transportation (DOT) specifications. Given the small market for beadlocks, this costly process is usually avoided. One exception to this is the AEV beadlock. There may be others.

A second concern is that beadlocks are difficult to balance. Again this is not quite true. A high-quality wheel of any design should balance without issue. Keep in mind that all YJ tires should be dynamically balanced.

One important fact to remember about beadlocks is the need for proper installation and maintenance. Most beadlocks have 32 bolts holding the outer ring in place. Bolts must be installed in proper sequence and to the correct torque. We torque in three stages, starting with 12 ft-lbs, progressing to 14 ft-lbs, and ending at 16 ft-lbs. We then double-check the torque of all bolts. Different wheel manufacturers may have different torque specifications. You must also check torque settings monthly to ensure reliability and safety. All bolts should be replaced annually. So unless you are very serious about four-wheeling, need beadlocks for the terrain you run, and are willing to put in the time and money for proper maintenance, stick with traditional bead wheels or the simulated beadlocks if you like the look.

Some of the larger, more aggressive mud-terrain tires have a thicker bead. This requires a spacer between the wheel and the beadlock ring to ensure a square fit and accurate torquing.

Ultra Wheel’s Xtreme Bead-Lock provides excellent strength and durability. This has been proven over many extreme off-road races and rock crawling competitions.

Insert the remaining bolts through the beadlock ring and start the bolts into the bolt holes on the rim. Snug all of the bolts without tightening.

Beadlock wheels allow the use of much lower tire pressures without the risk of the tire bead becoming unseated from the rim. The Raceline Monster beadlock wheel provides excellent strength. We know because we have tried to destroy them on several occasions.

With the beadlock ring removed, it is easy to mount the tire on the rim. With the tire on the rim, the beadlock ring is placed over the tire so that the bolt holes line up on the rim. There are 32 bolts holding the Raceline beadlock ring on the rim. Place the first 4 bolts at approximately 90-degree intervals and snug them down to set the tire and ring squarely in place.

Wheel Size

Wrangler YJs were sold with 15- and 16-inch-diameter wheels. The optimum diameter for a YJ is more dependent on tire availability and the tire brand you prefer. Not many off-road tires are available in 16-inch diameters and even fewer in 15-inch diameters. If you plan to install diameters no larger than 30 to 31 inches, stick with a 16-inch diameter wheel. This allows the maximum amount of sidewall height for most effective airing down. If you plan to upgrade the brakes, go up to a 17-inch-diameter wheel. Smaller-diameter wheels can have clearance issues with brake calipers.

Width

The widest wheel on stock YJs is 7 inches. This is too narrow for tires larger than 32 inches in diameter. Optimum width is 8.5 to 9 inches for 33- to 37-inch tires with a 12.50- to 13.50-inch section width. If you go extreme with 40-inch tires, then a 9-inch-wide wheel is needed.

Weight

Wheel weight is important, but given that off-road tires are heavy and the Jeep Wrangler YJ uses solid axles, the effect of wheel weight is minimal compared to the total unsprung weight of the wheels, tires, axle housings, gears, and half the weight of suspension components.

The most common wheel size for a YJ with larger all-terrain or mud-terrain tires is 17-inch diameter by 8.5- to 9.0-inch width. A typical steel wheel will weigh around 40 pounds, an alloy wheel in the mid- to high-20-pound range and an alloy beadlock with a steel retaining ring weighs about 44 pounds. The larger the tire and wheel combination, the greater the rotational inertia becomes. This can have a serious effect on braking. The stock YJ brakes were designed for 28- to 39-inch tires. Increasing tire diameter to 32 inches or more is cause for a brake upgrade.

Lug Nuts

If you use anti-theft lug nuts with splines, make sure you have the proper key socket that fits on your lug nuts. There are several sizes with different spline patterns. Always carry the key lug socket and the socket that drives the key because you never know when you will need it.

The lug nut key socket is used with anti-theft lug nuts. Be sure to carry the lug nut key socket in your Wrangler if you use security lug nuts.

Jeep uses dynamic wheel balancing for the Wrangler. The reason is simple: with large tires and high rotational inertia due to the heavy tire tread located away from the center of rotation, dynamic balancing reduces out-of-balance issues such as shimmy and death wobble. During dynamic balancing, the tire and wheel are spun at high speed until the location of imbalance is located on both the inside and the outside of the rim.

This 37-inch BFGoodrich mud-terrain tire and Raceline beadlock wheel measured less than 2 ounces out of balance on the first spin after mounting. After adding weights, the second spin showed nearly perfect balance at 0.25 ounces out on the inner rim. Perfect balance was achieved on the third spin. The fallacy that beadlock wheels are impossible to balance is clearly inaccurate!

Wheel and Tire Balancing

Tire and wheel balancing is important on all vehicles. On the YJ, especially with larger tires, standard static balancing is not adequate. The Jeep factory uses dynamic balancing on Wranglers. Dynamic balancing balances both the outside and the inside of the rim, which reduces wheel wobble and shimmy. The YJ is prone to rapid ball joint and rod end wear. This leads to shimmy and death wobble, especially when tires greater than 33 inches in diameter are used.

Tire Rotation

Normal tire rotation is even more important with larger tires on a YJ.

Choosing the Right Tires and Wheels

What is the best tire for your application? It really comes down to priorities. If you use your YJ as a daily driver, and especially if you have a long commutes, then an all-terrain tire is likely the best choice. If you drive in mud often, then a mud-terrain tire would work well. If driving off-road (especially on difficult trails) takes precedent over highway driving and tire wear and road noise are okay with you, then go for the aggressive mud-terrain tires.

Torque all of the bolts. It is best to torque in two or three steps. With the Raceline beadlocks, the first torque step is about 14 ft-lbs. The final torque is 18 ft-lbs. After a few miles of driving, recheck the torque. The beadlock bolts should be retorqued every 30 days.

Wheel backspace is critical on the Wrangler. Backspacing is measured from the back of the wheel rim to the mounting surface of the wheel to the hub. Too much backspace with larger, wider tires can cause rubbing problems, as the front tires are turned near full lock and at the extremes of vertical suspension travel.

There are dozens of tire choices for a Wrangle YJ. Here is a list of the tires that we have experience with. There are other good tires available, but we have not used them.

• BFGoodrich All-Terrain T/A KO2

• BFGoodrich Mud-Terrain T/A KM2

• Falken WildPeak M/T01

• Falken WildPeak A/T3W

• Goodyear MT/R

• Mickey Thompson Baja Claw TTC Radial

• Mickey Thompson Baja ATZ P3

• Mickey Thompson Deegan 38

• Hankook Dynapro MT RTO3

• Hankook Dynapro AT-m RF10

• Toyo Open Country A/TII

• Toyo Open Country M/T

• Nexen Roadian AT

• Nitto Mud Grappler

• Nitto Terra Grappler

• Nitto Terra Grappler G2

• Nitto Ridge Grappler

• Nitto Trail Grappler

• Maxxis Bighorn

• Maxxis Trepador

• Maxxis Creepy Crawler

• Firestone Destination A/T

• Pit Bull Rocker XOR

• Pit Bull Mad Dog M/T

• Pit Bull Growler

• Super Swamper TSL

• Super Swamper SSR

• Kumho Road Venture MT

If there are dozens of tire choices, there are hundreds of wheel choices. Wheels are a critical item and need to be strong and durable for off-roading. Select a good alloy wheel if you can. If budget is a consideration, go with a steel wheel. And if you wheel a YJ in extreme conditions, go for a good beadlock wheel. Since YJs are relatively lightweight, beadlocks become even more important if you run large, stiff sidewall tires and plan more extreme rock crawling.

Optimum backspace for 8.5- to 9.0-inch-wide wheels is 3.5 to 4.75 inches. The smaller the backspace measurement, the more the tire will stick out from the vehicle. The Raceline Monster beadlock has 4.5 inches of backspace.

Form Versus Function

YJ owners have many wheel choices. Some of the best-looking wheels have a minimal amount of material in the spokes. While these wheels are very strong, they are more susceptible to damage on the trail, possibly to the point of cracking or breaking in an extreme situation. If you plan extreme rock crawling in your YJ, go for the beefier-looking wheels.

Wheel Spacers and Adapters

Wheel spacers that slip over the wheels studs are not a good idea. Wheel adapters that have built-in wheel studs and bolt onto the wheel studs on the hub work better and are safer. Check the regulations in your state, as spacers and adapters are not legal in some states.

Wheel and Tire Care and Maintenance

Wheel lug nut torque should be between 90 and 100 ft-lbs, but check with your wheel manufacturer for the correct torque specification. Because of the more extreme conditions off-road, check torque often. If you remove lug nuts, retorque the nuts using a star pattern. After 200 to 300 miles of driving, retorque the wheels.

Torque on the beadlock bolts should be checked every 30 to 60 days. Having an equal torque around the outer ring is very important. If a bolt is broken, replace it immediately. We carry spare bolts just in case.

Wheel and Tire Cleaning