The Role of Air Pressure in Rugged Terrain Tires
![Matthew Guy](https://cdn-fastly.thetruthaboutcars.com/media/profile/2022/07/21/101521_1.jpg?size=91x91)
Any gearhead with dirt under their fingernails has seen slow-mo footage of an off-road beast slowly clambering up and over some difficult obstacle, suspension flexing and tires working hard to earn their keep. The more astute videographers might include a close-up of those same tires deforming slightly as they traverse the terrain.
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Rugged terrain tires bridge the gap between an all-terrain tire, and a more aggressive mud terrain tire. One of the best on and off the road is the RoadX RXQUEST R/T, a formidable tire meticulously crafted for trucks and SUVs. The RXQUEST is designed for on and off-road driving with deep, spaced lugs for gripping in dirt and mud, and tightly grooved and siped knobs for the best wet and icy road condition grip around. With a sturdy construction and specialized tread, it delivers everything you could need in a truck tire - durability, traction and on/off road ability. It is Three-Peak Mountain Snowflake Certified for winter driving conditions, meaning it will grip in snow, ice and anything else you might encounter on winter roads. There are a wide-range of sizes available, meaning no matter what truck or SUV you drive, there is likely an RXQUEST tire to fit.
But why? Is there a problem with the tires? Did the driver ignore a series of low-pressure warning lamps? Can I possibly work any more question marks into this paragraph? The answer to all those questions is negative. In fact, the tire’s appearance is quite intentional and serves as a great tool with which to grab a skiff of extra off-road traction from the already capable rugged terrain type of tire. Allow us to explain.
While not generally given much thought, the air inside a tire plays a vital role in supporting the vehicle and dictates how the tire interacts with the surface into which it is being pressed and is generally measured around these parts in pounds per square inch (PSI). Having too much of the stuff in a tire is called overinflation and can diminish how much tire surface, referred to as a contact patch, touches the driving surface. This can lead to reduced grip and odd wear.
Conversely, too little air pressure can make a larger and wider contact patch, creating extra rolling resistance the vehicle must overcome to maintain speed. Think about how difficult it was to pedal yer bike as a kid when there wasn’t enough air in its tires. The same principles apply.
But in an off-road situation, it can be advantageous to have a less-than-normal amount of air in one’s tires – particularly when navigating soft sandy surfaces or scampering up some slickrock at Moab. Reducing tire pressure (airing down, in off-road parlance) is a way to intentionally increase the tire’s contact patch, spreading the vehicle load over a wider surface area of rubber and permitting more elements of a tire’s tractive properties to be in contact with the ground.
In fact, tire companies have long caught on to this practice and have begun adding gripping surfaces to the sides of rugged terrain tires. The Saliun Terramax RT, for example, has a squared profile and staggered scalloped shoulder lugs with stone ejectors to maximize traction while removing debris in the voids. This is designed to dig into tough terrain when aired down. Other brands like BFGoodrich with its legendary KO2 and Nitto with the Ridge Grappler incorporate the same tricks to tremendous effect. It’ll take some creative or clueless wheeling to completely stymie these tires when properly inflated for the conditions. As a bonus, an aired-down tire will ride a bit smoother, as well.
Speaking of, finding the correct tire pressure for all conditions can take a bit of trial and error. This is why it is a decent idea to ask other drivers who have tackled the particular off-road obstacle you’re about to traverse for a bit of advice, or at least pay attention to posted suggestions in popular off-road areas like Moab or on the Rubicon. Invest in a high-quality tire pressure gauge (no, one from the dollar store doesn’t count) since they often include a deflator setting which can take a tire’s PSI down to a very specific measure. There’s no substitute for experience, so keep a few notes in yer phone or on a scrap of paper tucked into the console of your rig as reference points for the next time out.
Most off-road gearheads will suggest a higher pressure for rocky terrain than for sandy surfaces in order to ward off punctures and rim damage from jagged outcroppings. A lower pressure helps tires adapt and all but mold to the terrain, effectively gripping rocks and such like a human closing their fingers over an obstacle. Plus, slashing a sidewall far from roadside assistance is no joke. Meanwhile, the aforementioned sand (or mud) conditions often benefit from a relatively low tire pressure to promote better flotation. That said, if one plans on travelling at sustained felonious speeds on dunes, too little inflation can cause damage and loss of steering control
Generally speaking, it is better to err on the side of caution and not stray too far from the recommended pressures which are generally listed on a sticker in the driver’s door jamb of a vehicle. One can usually deflate their tires a bit further, if it safe to do so, more easily than adding air on the fly. Considering the last point, you’ve remembered to pack a portable air compressor to air up those rugged terrain tires after wheeling, right? Remember to immediately pump the tires to recommended factory pressures once returning to surfaced roads so you’ll have a safe drive home.
[Images: Manufacturer, Tricky_Shark/Shutterstock.com]
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![Matthew Guy](https://cdn-fastly.thetruthaboutcars.com/media/profile/2022/07/21/101521_1.jpg?size=91x91)
Matthew buys, sells, fixes, & races cars. As a human index of auto & auction knowledge, he is fond of making money and offering loud opinions.
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- 28-Cars-Later Suggestion for future QOTD: Given the fact US road infrastructure is crumbling around us why must all new cars have 20+ inch wheels with tires an inch or two thick in sidewall which literally become bent over time bc of potholes? I know initially in the 90s wheels got bigger to accommodate larger disc brakes but its gone a little too far given the road infrastructure don't ya think?
- Jeff Keep your vehicle well maintained and it will run a long long time.
- AZFelix "Oh no! Anyway... " Jeremy Clarkson
- SCE to AUX I can't warm up to the new look. Still prefer my 22 SF.
- SCE to AUX I guess the direct sales stores weren't polled. Unless dealers are going out of business, I don't feel one bit sorry for them. They should most fear the mfrs who are eager to get rid of them, reducing costs and increasing customer satisfaction.
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