As a motorcycle rider, do you know why it is important to check your tires’ air pressure? Do you know the correct procedure to check your tires’ air pressure? Do you know how often to check your tires’ air pressure?
If you've answered 'no' to one or more of these questions, you are not alone. In fact, Michelin engineers have observed that nearly one-third of all riders they encounter at safety seminars have motorcycles with improper tire pressure. This presents a clear learning opportunity for the majority of motorcycle riders. For others, this can be a refresher course to back up your good intentions with facts when your buddies look at you funny as you check THEIR air pressure. By the end of this article we hope you become an ‘Air Pressure Advocate’ that leads by example to ensure other riders take care of their tires and achieve optimum riding pleasure every time they jump on their bike.
A Tire is a Dynamic Component
Let’s back up and understand what your tires do for you as you ride. As you know, tires are the only part of your bike that touches the road—or the only part intended to touch the road. This means that it must transmit inertial forces associated with you, your bike and your gear under all phases of accelerating, braking, and turning. The tire is expected to do this—and do it well—in all weather conditions and on all road conditions. And, of course you expect them to perform no matter how aggressively you ride! These are the expectations tire designers are faced with when turning rubber and other chemicals into a dynamic component of your bike. The amount of research and development of a tire may span years from conception to the day it is mounted on the rim. Unfortunately all of the R&D value of this dynamic component is thrown out the window if the new owner (you) neglects to maintain proper air pressure.
Air Pressure Matters
Tire designers must account for several factors when developing a tire as mentioned above. To achieve all of the required tire performances, a critical assumption that they must make is that the tire is inflated to the correct pressure. However, as they know (and you may not realize) a tire is continually fighting to remain inflated. Rubber acts as a semi-permeable membrane—it is not altogether air tight. Even if the bead on the rim, the valve core, the valve stem, and the rim are all virtually air tight air will still diffuse through numerous tire layers. So without periodically re-inflating the tire, it will eventually and inevitably go flat. This is where you—the motorcycle tire air pressure advocate—comes in.
Have you ever come across an ancient barn find with perfectly inflated tires? I didn’t think so!
What Can You Do?
Now that you have an idea of how important it is for the tire to function properly and their natural propensity to deflate, we can discuss the not-so-obvious benefits of maintaining proper tire pressure. First, in order to reap any benefits, you must create a habit of checking your tires’ air pressure every two weeks and before long trips. All tires deflate—even new tires! After two weeks you may notice a significant drop in pressure, so it is your job as the operator to maintain proper air pressure according to the motorcycle manufacturer’s recommended specifications. You can find this information in your owner’s manual or on the Federal Motor Vehicle Safety Standards (FMVSS) placard found on the frame of your motorcycle.
It is important to know when to check the air pressure. Do so when the tire is cold. A cold tire is one that has not been ridden for at least two hours, or more than two miles at slow speeds. A general rule of thumb is that a hot tire will gain about 5 psi over its cold tire state. If you find that your hot tire pressure is above the calculated hot inflation pressure, NEVER bleed air from a hot tire.
Ignoring the proper inflation pressure means you don’t care about performance, longevity or cost savings—my next three topics.
Don’t Sacrifice Performance
Achieving the highest performance out of a tire requires proper air pressure. All of the dynamic forces that affect the performance of a tire are being transmitted from the bike to the ground through the contact patch of the tire, which is approximately the size of your palm, allowing for optimal grip and a safe, comfortable ride. As you may have guessed, the contact patch is greatly affected by air pressure. Too much pressure and the contact patch shrinks, the grip is reduced and you can expect a harsh ride. Low air pressure causes the contact patch to increase causing unsafe handling, an unstable sidewall and even damage to the tire casing. Riding on tires with improper inflation, especially under-inflated, is dangerous and a serious safety issue. Improper inflation can cause sudden, unexpected tire failure, which could lead to loss of control resulting in serious injury or even death.
Performance includes longevity. Everyone wants a tire that lasts. Proper air pressure is one of the best ways to get the most life out of a tire. Riding on underinflated tires is a leading cause of cupping and irregular wear, which affects handling but certainly the longevity of a tire.
Gauge it Correctly
Do you think you can tell if your tires are properly inflated by simply looking at them? Guess again. The rigid sidewall of some tires makes it impossible to visually gauge the air pressure, so don’t guess. Use a quality stick gauge (the one with a spring), a dial gauge, or digital gauge that you know provides consistent and reliable readings. Feel free to stop by your mechanic to compare readings against his gauges. Never trust the gauge at the end of a gas station air hose!
Did you know that riding on a flat tire—even for a few hundred yards—can cause catastrophic internal tire damage, which may go unnoticed? Never ride on a flat tire.
So, how much is ‘five minutes of your time every two weeks’ worth to you? The economics are easy. When a tire is underinflated, the irregular wear and added stress will reduce the life of the tire. Wearing out your tires is inevitable but with proper air pressure you can optimize the longevity, which will reduce the frequency of replacing your tires—no small expense, right? I’m sure you remember how much you spent on your last set of tires and the labor to mount them. Over time, ensuring that you maintain proper air pressure in your tires can add up to significant savings.
Your next step is to download and review the Michelin Air Pressure Guide, a quick reference of all the points covered here. Then become an ‘Air Pressure Advocate’ for your household or riding group by sharing these key points every time you check your air pressure. As a new Air Pressure Advocate, you can even share this article now (mask, long cape, and ‘Air Pressure Advocate’ written on your chest is entirely optional).