Back in the day, wheel and tire choices were limited. As time has progressed and vehicles have evolved, wheel and tire choices have more than kept the pace. A collage of options awaits the buyer. Do you need radial- or bias-ply tires? Are steel wheels better than aluminum? Is wheel offset the same as backspacing?
To make sense of the madness, we've put together a series of informational vignettes to make better sense of rolling stock.
Tires: Radial Or Bias Ply?
Two of the most popular tires for hardcore trail-riding and rock-crawling are the Interco IROK, a bias-ply tire, and the BFGoodrich Krawler, a radial-ply tire (or called simply a radial). The external differences are obvious, but there's more than meets the eye. Let's take a look at the internal construction of radial- and bias-ply tires.
Tire Tools For The Trail
Tire trouble strikes every off-roader. The minimum you should carry is a fullsize spare tire, a lug wrench, and a jack.
Steel Or Aluminum?
What's better? Like radial- and bias-ply tires, each type of wheel has advantages and drawbacks. Ultimately the answer isn't which is better. It's which is better for you.
How To Measure A Wheel
Are backspacing and offset the same thing? How do you measure rim width? What do you call the different contours of a wheel? What determines caliper clearance? We've got the answers.
Interco IROK: Bias Ply
BFGoodrich Krawler: Radia...
BFGoodrich Krawler: Radial
This diagram shows a BFGoodrich...
This diagram shows a BFGoodrich Radial Mud-Terrain T/A KM2. Notice that the internal steel cords go side-to-side from one bead to the other. This cord orientation allows the tire casing to flex more easily. Radial construction doesn't "fight" itself as the tire flexes, so a radial tire runs cooler. Since a radial flexes more easily, it is more adept at absorbing small bumps and conforming to jagged off-road surfaces. Extra plies are added across the top (or "crown") of the tire to increase puncture resistance. The radial tire's internal construction costs more to produce than a bias ply, so a radial costs more at the counter.
"Bias ply" is actually a poor...
"Bias ply" is actually a poor term. "Cross ply" would be a better description. In a bias-ply tire, the belts are arranged at crisscross angles, i.e. "on the bias." With a bias-ply tire, the sidewalls have the same construction as that of the crown. When a bias-ply tire flexes, the crossed plies "fight" each other. This internal struggle produces heat. The heat can break the tire down faster. Another byproduct of the cross-plies resistance is that the tire doesn't absorb small jolts as easily as a radial. What advantages do bias-ply tires have? Bias-ply tires are less expensive to produce, so they're easier on the wallet. Bias-ply tires tend to have tougher, thicker sidewalls compared to radials. Finally, the "dead" feeling of a bias-ply tire means that it won't bounce as much, which can be an advantage on steep climbs in the rocks.
The BFG Krawler was a breakthrough...
The BFG Krawler was a breakthrough for radial tires in the rocks. BFGoodrich strengthened the sidewalls and chose a tread pattern and tread compound specifically for rock-crawling.
Pit Bull Tires offers both...
Pit Bull Tires offers both radial- and bias-ply models in its lineup. Shown is the Maddog LT Bias. Super-tough sidewalls and an aggressive shoulder tread pattern are two reasons this tire works great in the rocks.
Bias-ply tires don't flex...
Bias-ply tires don't flex as easily over jagged surfaces. Airing down further than you would a radial lets them conform to rough ridges. Super-low tire pressures almost always call for beadlocked wheels.
Spares at the ready in a Baja...
Spares at the ready in a Baja pit.
This tire-repair kit takes...
This tire-repair kit takes up little room and provides extra layers of defense against tire trouble. Extra valve stems, tire plugs, T-handle plug insertion tool, valve-core wrench, T-handle probe (for roughing up the hole's edges, improving plug adhesion), patches, and rubber cement round out the list. You should also carry tire irons (not shown).
You'll need an air source,...
You'll need an air source, too. The Powertank is a long-time favorite.
Adventure or disaster? The...
Adventure or disaster? The supplies and knowledge you carry make the difference.
Steel wheels have been around...
Steel wheels have been around for eons. They're relatively inexpensive and easy to repair. Several styles are available, giving steel users choices when it comes to looks. Under stress, steel wheels will bend instead of breaking. They can be repaired in the field by pounding them back into shape with a hammer and a block of wood or a punch. This is cool: Black Rock Wheels makes its wheels in-house in the USA. We're taking a trip to the factory soon for an upcoming story.
Here's an aluminum Black Rock...
Here's an aluminum Black Rock Viper wheel. Like almost all aluminum wheels today, the Viper is a cast wheel. Aluminum wheels won't rust, are lighter than steel, reduce rotating and unsprung weight, and come in seemingly endless styles. They're not as easy to repair as steel wheels, but we found out that it's still possible to repair an aluminum wheel. More on this later.
Backspacing describes the...
Backspacing describes the measurement between the wheel's inward-facing edge and the wheel-mounting surface.
Wheel width is measured on...
Wheel width is measured on the inside from bead seat to bead seat.
Offset describes the relationship...
Offset describes the relationship of the wheel-mounting surface relative to the central plane of the wheel. Negative offset means that the wheel-mounting surface is toward the vehicle. Positive offset means that the wheel-mounting surface is toward the street.
Here's a cross-section of...
Here's a cross-section of a wheel with an OMF beadlock on the outside and an OMF weld-on reinforcement ring on the inside.