Tire pressure is an age old discussion among UTV and ATV enthusiasts, each one thinking they know the secret decimal to perfect offroading. The truth is, they're all probably right. The perfect tire pressure is a spectrum, and we're here to offer our advice on where to start and you can air down/up to your liking.
What is the best UTV tire pressure?
Whenever we mount up a set of wheels and tires, we always start with a PSI spec of 15 lbs. Not to squishy, not to firm, 15 is the best balance of hardpack and crawling. Make note, if you plan to exclusively ride on hard pack at high speeds, consider starting at 18-20 PSI. Alternatively, if you roll off the trailer and you're crawling 95% of the trail, you may consider dropping down to 10-12 PSI for that extra bite when you need it. When in doubt, consult your owner's manual and use the OEM spec set at your dealer.
Does Elevation Affect Tire Pressure
Significant changes in altitude affects tire pressures when traveling from one elevation to another. Fortunately, this influence is relatively small. As altitude increases, atmospheric pressure decreases. If you are planning to ride on a trail that climbs 1000+ ft, do a test. Record your tire pressure at the trailhead and then at the top and you'll see your tire pressure has increased.
Does Temperature Affect Pressure?
The tire pressure recommended in your vehicle's owner's manual is the manufacturer's recommended cold tire inflation pressure. This means that it should be checked in the morning before you drive more than a few miles, or before rising ambient temperatures or the sun's radiant heat affects it.
Air will expand when heated and contract when cooled. This makes fall and early winter months the most critical times to check inflation pressures. The rule of thumb is for every 10° Fahrenheit change in air temperature, tire pressures will change about 2% (up with higher temperatures and down with lower).
In most parts of North America, the difference between average summer and winter temperatures is about -50° Fahrenheit…which results in a potential loss of about 5 psi as winter's temperatures set in. And a 5 psi loss is enough to sacrifice handling, traction, and durability!
Does Tire Pressure Change Over Time?
Since typical tire pressures range from 15 to 25 psi for UTVs, there is a constant force trying to push the air through the tire. This allows some of the air to escape (called permeation) right through the microscopic spaces between the rubber molecules. And somewhat like a rubber balloon, the air will eventually escape if it is not replenished. All things being equal, a tire's inflation pressure will go down by about 1 psi every month. This means that if air isn't added for two to three months, the tire's inflation pressures will probably be 2 to 3 psi low.
Disadvantages of Underinflation
An underinflated tire can't maintain its normal shape and becomes flatter than intended while in contact with the road. This can lead to premature tread degradation by as much as 25% compared to OEM recommended pressure. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would experience a significant loss of steering precision and cornering stability.
Disadvantages of Overinflation
An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced (hence why people deflate when rock crawling). If a UTV's tires are overinflated by 6 psi, they could be damaged more easily when running over obstacles or rough terrain, especially at higher speeds. Higher inflated tires cannot isolate trail irregularities well, causing your ride to be much harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point.
Note: While we're discussing correct inflation, don't forget to check your spare tire combo while you're at it. You don't want to be in a pinch and have your spare fail as well.