Ask The Editors: Do My Tires Breathe?
Dear ATVC:
All your performance guides stress the importance of checking your ATV’s tire pressure. Well every time I check mine, it’s never the same as it was the time before and no it’s not a leak because the pressure isn’t always less. What gives?
In short the air inside your machine’s tires is still air. What does that mean? It means the molecules expand when it’s hot out, constrict when it’s cold and fluctuate with changes in elevation and humidity level. What’s more, the temperature of the tire carcass itself affects the air in there!
When ambient temperature decreases, tire pressure actually decreases as well. When the temp rises, the opposite takes place. Just how much of a change are we talking here? Well leaving your quad out in direct sunlight on a warm summer’s day can easily increase pressure in each tire by several pounds due to the nature of expansion. Considering even a ½ pound difference on either side of the quad can cause the machine to pull to the lower pressurized side, the importance of making sure you’re starting out with even pressure across all four tires becomes very clear.
What’s especially boggling is that filling/ checking your air pressure in the cool morning can result in inaccuracies when compared to checking again after a few hours of riding (friction) after the heat of the day arrives.
Here’s the good news- tire manufacturers realize that this is the way of the world and hence select compounds designed to stretch and constrict to compensate. Because of this you’ll notice the manufacturer recommended pressure stamped on your tire’s sidewall is rarely just one number but rather a range (example 6-9 PSI).
Remember that your machine’s tires are responsible for everything from the ATV’s steering to its suspension performance, braking and even overall handling, it’s with good reason we always recommend checking your tire pressure as a starting point for fine- tuning your ATV’s performance.
