Tech Tips

Tire Pressure 101

Written by  June 30, 2005

There is a regular schedule that we should keep when it comes to our motorcycle tires. Keeping the air at a specific pressure is a challenging task that may get overlooked. The average do-it-yourselfer has so many other areas that he or she might want to focus more attention on than the tires, and many riders tend to ignore this important maintenance task—you know who you are—you just check your tires when you stop at a gas station when filling up (or maybe not)!

Motorcycle tires are far more advanced than you might think these days. They have many different factors and stresses. Since you only have two, you must ask yourself, what can I do to extend the life of these high-dollar donuts? Let’s get down to the facts of what happens if your tires are under-inflated or over-inflated.

Under-inflated tires can result in imprecise cornering, higher running temperatures, irregular tread wear at the edge of the contact patch, fatigue cracking, overstressing and eventual failure of the tire carcass.

Over-inflating your tires does not increase load carrying capacity, but will result in a hard ride and accelerated tire wear in the center of the contact patch.

For high-speed, fully loaded, dual-riding or touring motorcycles, inflate front tires to the maximum pressure recommended by the vehicle manufacturer. I have always referred back to the VIN (vehicle identification number plate) on the frame or front steering stem of the bike. When dealing with touring tires, they must be inflated to a minimum of 36 psi for light to medium loads and 40 psi for dual riding and other loads. Never exceed the maximum load indicated on the tire sidewall or the vehicle capacity load found in the owner's manual. This will tend to wear out the tires much faster and give the suspension a workout.
One other thing that is very important is to check the tire pressure when cold. No exceptions! It's important to remember that your vehicle's recommended tire pressure is its "cold" tire inflation pressure. It should be checked in the morning before you drive more than a few miles; otherwise rising ambient temperatures or the sun's radiant heat affects it. Since air is a gas, it expands when heated and contracts when cooled. In most parts of North America, this makes fall and early winter months the most critical times to check inflation pressures. 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. A 5 psi loss is enough to sacrifice handling, traction, and durability!

I recommend that you check cold tire pressure frequently with a good quality gauge that holds a reading. I purchased a spring-loaded gauge from Snap-On Tools, and it has lasted for more than six years. Where you buy your gauge is entirely up to you, but the old phrase “you get what you pay for” stands true. The $2 gauge at the counter of your local auto parts store might work for awhile but don’t bank on the reading to be correct.

The tires on your bike need weekly attention, both a visual inspection as well as a pressure check, and do not forget the valve core. This is a serviceable part that holds the air in the tire, plain and simple. If you notice that you are losing pressure, this may result from undetected tire damage. Visually inspect tires for punctures, cuts, abrasions, cracks, bulges, blisters or knots. It will be necessary to dismount the tire to complete an inspection for internal damage and any need for repair. Only certain punctures in the tread area may be repaired, and only if no other damage is present. Tires with nonrepairable damage must never be used again. Damage caused by impacts or debris penetrations can result in sudden and complete tire failure and accidents. Always inspect tires following curb, chuckhole or other impacts, evidence of penetration beyond the tire surface, bulges or low pressure. Do not continue riding on such tires. Stop and call a friend for a trailer or pickup ride.

With that said, you can easily see now how important it is to have the tires’ pressure and condition at their best. Keeping these simple items in order will not only give you the long life that you expect but also great tire wear, handling benefits and optimum gas mileage as well. There is no “tough-o-meter” scale on this tip. We all need to do this on a routine schedule. Inspect your tires frequently for damage and always heed warning signs such as vibration, handling instability, rubbing or tire noise that occurs during operation of the motorcycle

Happy 4th of July and B-Safe!

By Dave Miller