Truck Tire Tech - Anatomy Of A Tire

Let's work backward: The term "directional" tire was born out of the ultra-high-performance tire industry, and the design was aimed at getting water out from under the tread at very high speeds. The directional could spit water from the center of the tire outward-a regular parting of the seas-to help wet and straight-line performance. The theory tends to be carried over for mud tires for the same reason and also for self-cleaning. Putting the tire on in the wrong direction could lead to hydroplaning, more noise, and usually weak-arse performance overall. So don't.

Since you've been paying attention, we know you understand when we say BFGoodrich's Krawler T/AKX has aggressive lugs in the tread and sidewall, a four-ply nylon carcass, a tri-polymer tread compound, and slightly angled alternating plies. The technology behind the tire originated with BFG's CORR racing rubber.

Since you've been paying attention, we know you understand when we say BFGoodrich's Krawle

A "mild" tire is generally designed with more rubber than void, making it good for regular highway driving. There could be solid ribs for the tread pattern rather than grooves all the way through. That's not to say it won't function off-road; it could be an all-around performer, making it smooth on the street, but capable of light wheeling on the weekend. It's usually made from a softer compound, which tends to wear quicker than hard compounds. An "aggressive" tire typically has a more durable compound to help with cutting/chipping of the tread and puncture resistance off-road, and features more void than rubber as well as deep lugs for digging, sort of reminiscent of a tractor tire. Because there have been some compromises toward off-road traction and cut resistance, it may not wear as well and will probably seem noisy to you. That's because it is noisy since there is more void.

An "all-terrain" tire therefore could be the definition of mild. Its design is intended for it to perform good enough in all terrain-street, snow, wet, and mild off-roading. It's kind of the ultimate compromise in tire performance in order to give you a little taste of everything. A "mud" tire has a compromise toward performing on softer terrain, such as sand and mud. There's a little more tread void, so a lot more area to bite at the surface and fling it out as well as float across. And a "rockcrawling" tire commonly is larger, with tougher tread elements, but also soft enough to conform to and grip rocks. But the compound that makes the tread more difficult to cut or chip will likely compromise it in snow and rain, and it'll give up some road manners too. Does that mean a mud tire should never see rocks? Heck no. Those big lugs have been known to do really well in non-bog situations. The big picture is that all-terrain/mud/rock tires fall under the umbrella of light-truck tire, which means they're designed to shoulder a little more abuse than a passenger tire, so the carcass will be more robust for each.

It used to be that a "tall" tire was 35 inches. That's downright normal nowadays. A "fat" or "skinny" tire is mostly referencing its footprint width, or the width of rubber that is in contact with the street or trail or rock. Therefore, a "wide" tire has a wider footprint than a "skinny" tire. A "tall" tire is often the right pick for mud because it typically has a longer footprint for digging hard. But remember, as the tire size gets bigger (and therefore heavier), you need to make sure your truck is up to the task of running them-your stock brakes, axle, engine, and so on may not be able to handle the additional demand of rotating the major mass.

The X-Terrain has what Pro Comp calls Tri-Ply, three full-ply sidewalls matched to two steel belts as well as a nylon rap. Using our fingers we counted a six-ply tread, which is then coupled with XTC, their secret-formula Xtreme Traction Compound.

The X-Terrain has what Pro Comp calls Tri-Ply, three full-ply sidewalls matched to two ste

Atire's speed rating is the max speed it's certified to run, while the load index is the max load the tire can carry. When you're upgrading to a different tire size, you'll want to make sure the load index and speed rating are comparable to the OE-tire figures to keep things safe. So, don't go lower than stock for either.

The tire's profile refers to sidewall height. That means a low-profile tire has less sidewall. The aspect ratio (or series) is the ratio of sidewall height to tread width. If you take the Pro Comp Mud Terrain in size LT285/75R16, that 75 denotes that the sidewall height is about 75 percent of the tire's width. The higher the number, the taller the sidewall will look. Width is measured sidewall to sidewall and height is from the top of the tread to the wheel rim. Tread width is measured from side to side, while the depth is tread surface to the bottom of its grooves in 32nds. Pro Comp's Mud Terrain has a tread width of 8.65 and a tread depth of 18.5/32 (on average, truck tires are 17/32).

Another tire term that's popping up a lot lately is run-flat. That tire has a sidewall constructed in such a way that it can run without air and still support the weight of the vehicle for a certain number of miles at a specified speed or less. This is typically found in low-profile tires; since off-road-oriented tires have higher sidewall dimensions, it's difficult to make them into run-flats.

Your tire is full of numbers and letters that seem like internal codes. Here's how to crack 'em:

Let's take a Pro Comp Mud Terrain in size LT285/75R16. The "LT" is for light truck (passenger tires have a "P"). The first three numbers are the overall width of the tire, sidewall to sidewall. That number usually is listed in millimeters, so to switch to inches, divide it by 25.4. The next number is the aspect ratio. The "R" signifies that it's a radial. And the final number is the wheel diameter that will fit. Follow this formula to translate, although keep in mind that dimensional tolerances in one LT285/75R16 tire can make it differ from another with that same size designation:

Or, you can figure it out as flotation size. A 35x12.50R15 breaks down as follows: 35 is its overall diameter, 12.50 is the width, and 15 is the rim diameter.