Tire Air Pressure

What's the best air pressure to use for the terrain?

Published in the May 2018 Issue May 2018 Feature Adam Lukoic

Pssst. Let’s get you caught up on the highs and lows of tire air pressure.

Before we get into it, do you know what air pressure or PSI (Pounds per Square Inch) you are running in your tires right now? How long has it been since you checked? If you are like most people it’s probably been a while since you’ve checked.

More than likely your air pressure is lower than you think and it’s probably quite a bit lower than the recommended air pressure stated in your vehicles owner’s manual or the recommended PSI stated on the sidewall of the tires (which by the way, can be two completely different recommendations).

So which one do you go with? The owner’s manual recommendation or what’s stamped on the sidewall of the tire? And what air pressure is the best for different riding terrains? Can you run the same tire air pressure in the desert as you would mountain trail riding or even rock crawling? Let’s explore that.

Before we talk about what air pressure to use for different terrains and riding styles let’s address the differences between the PSI recommended in your vehicles owner’s manual and the recommendations on the sidewall of your tires. The PSI recommendations from your vehicles owner’s manual are based on the specific tires your vehicle came with from the factory. The PSI stated in the vehicles owner’s manual is suggested for general use and will need to be adjusted depending on your specific riding needs.

Tire Technology

Now let’s review some tire technology. All ATV and UTV tires should have a specific ply-rating and load rating indicated on the sidewall. The tire should also indicate a specific max PSI needed to achieve those indicated ply and load ratings. All three (ply-rating, load rating and PSI) are connected and need to be taken into consideration when determining what air pressure to use. Ply-rating is just that: a rating. It doesn’t mean your tire will actually have 4, 6, 8 or even 10 plies.

The max load rating of a tire and the corresponding max PSI can be a better indicator of a tire’s overall performance potential or limitations. When tire companies build a tire they build them to pass certain load rating specifications. Depending on how a tire is constructed, the type and amount of material used in the tire, it will determine how much air pressure is needed to achieve the specified load rating. That in turn will also help indicate the relative ply-rating or implied strength of the tire.

For example, a 6 ply-rated tire with a load rating of say 600 lbs., could have a recommended max air pressure of 8 to 20 PSI or even higher, depending on how the tire is built. This means you would need to use the recommended 8 or 20 PSI in that tire to achieve the indicated max load rating of 600 lbs. and the corresponding 6 ply-rating (implied strength).

Running correct air pressure is SO important because the max load rating and ply-ratings are linked to specific max air pressure. So what does it mean when you run air pressure lower than what is recommended on the sidewall of the tire? Yep, you guessed it, it reduces the max load-rating and corresponding ply-rating or implied strength characteristics of the tire. Running the wrong air pressure (too low or too high) is one of the leading causes of premature tire wear or total tire failure. Under inflated tires can run much higher temperatures due to carcass flex which causes friction and can become more susceptible to carcass damage from impact with objects on the trail, i.e., sidewall punctures.

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