Quick Tips: Tire Pressure Theory
Many pilots think they will be able to tell if their tire pressure is low simply by looking at them or "kicking the tires." What they aren’t aware of is that there "ok" looking tires can often be off by 50% or more.
Low tire pressure costs money!. The reason for this is simple, yet one that most pilots can miss. The wear on your tires directly indicates how you’ve “aired” your tires over the past year. 
In a nutshell, your aircraft tires last the longest (by wearing more evenly) when the tire pressure is right for the load it is carrying. If you continually operate them at a pressure even slightly lower or higher than what they should be, you are shaving wear time off of the life of your tires.
"An even, uniform tread pattern occurs when the tire pressure is right for the load it is carrying."
The most common tire defect is low tire pressure. Too little pressure in the tire makes it pushes the middle of the tread farther in, forcing the tire to run on the edges. You end up with a tire worn out prematurely on the sides, like the tread pictured to the right.
Too much tire pressure can cause problems too. Excess tire pressure "balloons" the tire in the middle of the tread, causing premature wear in the center, as pictured to the right.
An even, uniform tread pattern occurs when the tire pressure is right for the load it is carrying. This can vary quite a bit, depending on your aircraft's gross weight. Fortunately for us, the engineers have already figured all this out for us and printed it up nicely in most aircraft POH’s. Check yours out today and get those tires up where they should be. You'll being flying safer and you'll be padding your own wallet.
Charles Stence is an A&P/IA with many years experience inspecting, repairing and maintaining South Florida aircraft.