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Off-Road Tire Tech, Part II

Traits of tread types

Just as a good tracker can tell a lot from a trail of footprints, the tread design of a tire reveals much about its traits. You don't have to be Tonto, though, to figure out what the trail signs mean. Tire manufacturers make a wide range of truck and SUV tires designed for specific types of terrain. (See Part I of this feature for details on sizing, performance and suspension issues.) For instance, if you have an "asphalt four-wheeler," you can choose a tire design that works best on pavement such as one with an all-season tread pattern. All-season tires are designed for the average four-wheeler whose vehicle spends 95 percent of the time on-road and the other five percent on dirt or gravel roads.

Season to Surface

All-season tires are generally not constructed as beefy as some other designs, so they're more easily damaged when driving off-road. They work great in snow, however. Moving toward the purely off-road end of the spectrum, all-terrain type tires are just that—all-terrain. They can provide good performance in a wide variety of conditions, but don't excel in any one area. These heavy-duty tires have extra plies under the tread and in the sidewalls. Road noise is low, mileage is high and the better designs work well off-road.

For even more off-road utility, Baja-terrain tires are extremely heavy-duty tires designed for the off-road or desert racer that must endure a lot of punishment. Although they work very well, these tough tires can be expensive.

If you don't plan to go off-road in the dry desert, a mud-terrain tread has large lugs and open areas to handle, you guessed it, muddy conditions (rock crawlers like them, too). The void areas provide a channel for the mud between the tire's lugs to escape, so the tread doesn't become packed with goo and lose traction. The large voids help the tread to fling mud off (that's how those off-road trucks get so dirty) and prevent the tire from turning into a slick. The voids also offer good snow traction when driven off-road, but for snow on pavement, an all-terrain works better. Before you throw a set on your truck, keep in mind that mud-terrain tires are noisier on the highway compared to the less aggressive tread designs, and also wear out more quickly. On the other hand, these mud designs are also good performers in the rain because the large voids also route the water away from the main tread.

Now if you want to get really down and dirty, mud boggers have even larger voids for increased self-cleaning capability in extreme off-road conditions. This allows them to grab tight, spray mud, climb boulders and howl on the highway. While some rock crawlers prefer this tire design because they think the big lugs help the tires to grab the rocks, others believe a tighter tread pattern works better on rocks because of the greater contact patch.

Preferences aside, you can't beat a mud bogger during the rainy season. Just know that they have poor highway habits. Most tires in this class are bias-ply designs featuring very heavy-duty construction with a soft rubber compound for maximum traction. This means they'll be short-lived on the street, but off-road they'll prove durable and provide excellent traction.

Whatever type of off-road tire you select, be honest with yourself about the real-world use of your truck or SUV. An all-season tire doesn't have the right stuff for hard-core rock crawling, and you'll soon grow tired (no pun intended) of the drone of a mud bogger on a daily freeway commute. When it comes to reading the signs of off-road tire tread, think like Tonto and you'll stay on the right trail.