Tire Selection 101: The Basics for Picking an Off-Road Tire

There's more to rubber than meets the eye

Jan. 23, 2018 By Stephen Elmer

Buying a new set of tires can be an information overload, especially if it's your first time. There are rubber compounds, tread patterns, and more to consider, not to mention a big price tag making it a high stakes choice. After all, you don't want to spend your hard-earned money and be disappointed.

The key to tire happiness is a little research and education, which is why we spoke with Woody Rogers from TireRack.com, a product specialist that knows how to pick a tire. Rogers explained all the basic aspects of a tire that you need to know before buying, though the first step has nothing to do with actual rubber.

Be Honest

Before you even need to consider tread patterns or rubber compounds, Rogers says the first step to picking your tire is to be honest with yourself when identifying exactly what the use of the tire will be. How often will the tire really be off-road versus ferrying the kids to school?

This will help you determine what compromises you're willing to make, because with any set of purpose-built tires, there is bound to be a compromise somewhere.

"Lots of people overbuy tires," according to Rogers, a classic scenario of folks buying with their eyes and not necessarily their consumer smarts.

Tire Selection

A good way of approaching tire selection is to consider the most extreme situation the tire will be in, how often the tire will be dealing with that and how you would like the tire to perform in that situation.

For example, if you know that your tires will spend 90 percent of their time on pavement and the most pressing situation they'll find themselves in is muddy, wet country roads a few times in the summer, an all-terrain tire would be your best fit. All-terrains offer more grip, better debris ejection and more protection than a standard Light Truck tire with the trade off being slightly more road noise and a small decrease in fuel economy.

At the other extreme, if you have an off-road rig that will only see pavement 30 percent of the time as it drives to the trails, while the other 70 percent of its life will off-road, this will help you towards a decision. If this is the case, you'll need to further consider the type of off-roading that you'll be doing, as lots of mud and water will require a different tire than crawling rocky cliffs in Arizona.

This would be the difference between getting a mud-terrain tire or a dedicated rock crawling tire, and what you need will be indentified when you list all your potential uses for the tires.

The Real Details

Once you have a type of tire in mind, you'll need to dig into the details like the rubber compound and tread pattern. The rubber compound used in the tire will determine how the rubber flexes and grips the ground and is especially important when different temperature extremes come into play.

Most mud-terrain and similarly aggressive off-road tires have soft rubber compounds to help them flex around obstacles to grab hold. This is great at temperatures above about 45 degrees Fahrenheit (every tire has an ideal operating temperature that the manufacturer doesn't list, but this is a good rule of thumb), though when the thermometer shows cold creeping in, these soft tires harden up, causing them to lose grip.

Many AT tires are also only good above 45, though there is a growing number marked with the M+S (mud and snow) rating. While these tires should perform better in the cold than a tire without the rating, the only way to conquer winter weather is get a tire with a proper rubber compound that allows it to stay flexible in the winter time.

Tread pattern has a lot to do with grip as well, and noise. You'll notice that most passenger car or LT tires have straight treads spaced closely together, resulting in quiet highway operation but less grip. As you move into an all-terrain tire, tread spacing starts to open up allowing for bigger biting edges and better debris ejection but resulting in more road noise.

Moving up to proper mud terrain tires, tread spacing is large, providing big biting edges and great debris ejection, but also way more noise on the road. The tread pattern you choose will be directly influenced by the compromises you are willing to make, as more extreme performance comes with more downsides in everyday use.

Overall toughness of the tire is also an important consideration, as anyone dropping big money on a new set of rubber definitely wants it to last. Each manufacturer has a wear rating for its tires, letting you know how many miles of proper use will result in serious tread wear. Rogers says this rating is a general rule on what to expect, but "don't bank on it, especially in the off-road world."

So if the wear rating can't be trusted, it makes sense to get more plys and therefore a thicker, stronger tire, right? While this is true, when you're looking at tire thickness the answer isn't so simple. 

Adding plys to a tire adds weight and cost, and there is a point of diminishing returns where the thickness is overkill and just makes the tire too heavy.

A good example of where testing is applied can be seen with the BFGoodrich T/A K02. It actually lost a ply in its current generation, going from three to two, because BFG found that more protection in the shoulder and at the top of the sidewall was more important, and if a puncture happens on the lower sidewall, it was probably going to happen anyway. So the brand took away a ply and reinvested the weight in other areas.

Beyond that, "a thinner sidewall will grip better," Rogers tells us. "A thick sidewall is stiffer and won't grab as well. So more sidewall isn't always the answer." So the bottom line is, more plys isn't always better, and you'll need to research your tire selection before buying to see how protected the sidewalls are.

Size is another important factor in tires, and in the off-road world, tires are continually becoming larger and larger.   Upsizing your tires can bring the added benefits of more ground clearance and more sidewall, the latter of which will help your ride absorb some of shock of off-roading and adding more space for treads that may run down the side of the tire. But, beware of tire rub.

Going too big can result in your tire rubbing against your vehicle when you turn sharply, a situation that is most commonly avoided by lifting the body of the vehicle and/or installing high-clearance fenders.

There is a measurement process you can go through to confirm the largest tire that will fit on you vehicle, but before breaking out the tape measure, there is an easier way to find out. First, consulting the owner's manual of a vehicle will usually give you info on the largest tire that will fit. Second, checkout websites like TireRack.com, which allow you to search for your vehicle and get a list of all the tires that will fit.

As a general rule, most half-ton trucks can now run 33-inch tires without rubbing, though stepping up to 35's or larger will take some kind of modification.

Buying Time

There are plenty of resources out there for buying tires, with just about every individual manufacturer having a website where you can check for tire sizing and pricing. TireRack.com is another solid resource where you can go to see tires from all brands. You can get sizing information and read consumer reviews on all of the tires available, to see what owners are saying. Also check out TireReviewsandMore.com.

Research is the key behind buying the right type of tires for you and your truck, SUV, or trail rig. Just remember, be honest with yourself and your uses, and you'll come away with a tire that keeps you satisfied.

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