Choosing Tires & Tire Tech For Your 4x4 Truck - Beefy Tire Tech

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Tire Construction
One area of significant advances in tire composition for the 4x4 market have been in the strength and protection of the sidewall against puncture from rocks, tree roots and other trail debris. Goodyear recently introduced the Wrangler MT/R with Kevlar. This tire uses DuPont Kevlar in the sidewall to provide at least 35 percent more puncture resistance compared to other Goodyear tires. (See our review on page 66 for more.) BFGoodrich uses its TriGard technology-a combination of aggressive sidewall lugs, cut- and chip-resistant sidewall compounds, and stronger sidewall cords-in the new Mud-Terrain T/AKM2 and Krawler T/AKX tires. Pro Comp and Mickey Thompson both use three-ply sidewalls to provide protection.

Another category of tire construction is rubber compound, or the chemical composition of the actual rubber. Softer-compound rubber makes tires more flexible and gives them better grip on pavement and on rocks. But softer compounds also wear at a greater rate, giving you fewer miles before it's time for a new set. It's a trade off, a lot like horsepower and fuel economy. If you opt for a truck that gets 25 mpg, you're probably going to spend a lot of time waiting to get to 60 mph each time you get on the freeway. Choose the 400hp engine, and you'll have to live with 10mpg fuel economy. But there are plenty of options in between to create a compromise that's right for you.

Every once in a while, you'll hear someone waxing on passionately about how good bias-ply tires are for off-road driving. Usually these guys have a permanent three-day beard, have never actually bought new tires (ever), and they prefer not to be concerned with modern advances like phones. (Hoo-boy, here comes the hate mail.-Ed.) But since people talk about them, here's a basic explanation of the two primary types of tire construction: Bias-ply and radial.

Bias-ply is the older way that tires were manufactured, with layers of cords (usually made of nylon) applied diagonally to the centerline of the tread, in alternating angles. A strong bias-ply tire requires more layers, but this holds more heat, adds weight and creates a stiffer tire. This construction does provide very good sidewall puncture resistance when six or so layers of cords are used in the construction. Another reason that bias-ply is favored with some four-wheelers is that the original 4x4 tires with aggressive tread patterns had this construction. Bias-ply tires used today are usually very specific in application, and are generally reserved for utility trailers and agricultural use. There are some extremely large sizes where bias-ply construction is the only type available, and if you are building a mega-tired monster rig for an event such as Top Truck Challenge, bias-plies may be your only option.

A radial tire is composed of steel cable belts, applied bead-to-bead (i.e., at a 90-degree angle to the tread face) and coated with rubber. To make a stronger radial tire, larger steel cables can be used. The overall composition of a radial tire manages heat much better, creates a more flexible sidewall for better ride characteristics and has a more stable tread patch.

Because of the advantages of construction, radial tires have won out in the mass market. That's not bad for the 4x4 market, as a radial offers very good sidewall flex with stable tread surfacing, better fuel economy, longer tire life and a good ride. Advances in off-road-specific technology such as additional sidewall protection and aggressive tread patterns make radial tires a very good solution for almost all 4x4 applications.

Conclusion
Which tire is right for you depends on a few key factors: what's the most important use of your 4x4 that you want to optimize tire performance for, if looks are important and desired size. Any one of these three can be the dominant factor in your decision, but notice we didn't say how you will use your vehicle. How you want to use it is much more important in making a tire decision you'll be happy with. If you want the best mud performance, even though you'll only go mudding once or twice a year, it would be much more practical to go with an all-terrain tire, but you're probably going to be happiest with a mud-terrain tire. Be honest with yourself and closely evaluate the compromises of each decision. Tires can be the best purchase you can make for your 4x4.

Reading a Tire
Like so many things in the automotive world, reading tire size can seem like a secret code. Here's the decoder ring so you can be a cool kid in the club

Tire size can be displayed in two forms. The first is a traditional off-road size designation and is pretty straightforward. In this form, a 33x12.50R16.5 tire is 33 inches in diameter, has a 12.50-inch tread width and fits on a 16.5-inch wheel. The "R" designates it as a radial tire.

If you thought metrics would go away when you left school, guess again. The more common tire size designation is a metric measurement. In this photo, 315/70R17 is shown and is broken down as follows:

315 = overall width of the tire in millimeters
70 = is the aspect ratio, or the approximate sidewall height of the tire as a percentage of the tire width (70% of 245mm tire width = 171.5mm sidewall height)
R = radial
17 = wheel diameter in inches

Other information you will see near or embedded in the size designation is a two- or three-digit load rating. This number corresponds to the weight capacity of the tire. Usually, you don't need to look up the weight capacity in a chart, however, because it is found elsewhere on the tire with the recommended tire pressure.