Tech Tips

Motorcycle Tire Dry Rot

Written by  July 31, 2004

Motorcycle Tires are subjected to the harshest environments there could possibly be (Planet Earth). In addition to being stretched millions of times as they roll through their life, tires are exposed to acid rain, brake dust, harsh chemicals, direct sunlight, as well as summer's heat and abuse. And while a tire's compounds have anti-aging chemicals in their DNA, exposure to the elements will eventually cause rubber to lose some of its strength and allow cracks to appear.

The surface cracks that occasionally appear have been called many things; weather checking, weather cracking and ozone cracking, to name a few. These small cracks typically develop in the sidewalls or at the base of the tread grooves. Let’s face it; tires are the most important maintenance item between you and the road, and with to the cost of tires today, we must get every mile we can out of them.

Because all tires are made of rubber, they will eventually show some type of cracking condition, usually at the end of their life. However, this cracking can be accelerated by too much exposure to heat, vehicle exhaust, ozone and sunlight. For example, a vehicle parked outside year round instead of in a garage will constantly be exposed to the rays of the sun, increasing the likelihood of cracking. Additionally, sidewall cracking has been linked to abrasion from parking, or the excessive use of tire cleaners and dressings that remove some of the tire's anti-oxidants and anti-ozone protection during every cleaning procedure. Interestingly enough, when sun exposure or excessive cleaning is the cause of the small cracks, the sidewall of the tire facing outward will show damage, while the sidewall facing inward is rarely affected.
The anti-aging chemicals used in the rubber compounds are more effective when the tire is 'heated up' on a frequent basis. The repeated stretching of the rubber compound actually helps resist cracks from forming. The tires on motorcycles that are rarely ridden and accumulate low annual mileage are more likely to experience cracking due to long periods of being parked or in storage.

Although we are talking about motorcycle tires, this song remains the same for automobiles as well. We must ask ourselves; is the air pressure in our tires up to spec, or can we just skip it until the next service. I recommend that you frequently inspect your tires and check the air pressure when your tires are cold; or at minimum, every two weeks. Most motorcycle manufacture place the recommended PSI rating on a tag attached to the steering stem. If you follow the manufacturer’s recommendations, your tires will last a long time.

If you notice cracks on your tires, you need to replace them. It is an easy fix and a smart choice. I have seen tires in my own arena that are just flat out terrible. When you add a passenger on your bike, you are increasing the structural sidewall load of the tires. If the tires are showing signs of cracking, you could easily have a blowout and an accident. Not good for a first date! We must always think of our safety and the safety of others, by having our tires replaced as soon as possible. When you wash the rims on your motorcycle, the cleaner you are using could be harsher than you think on your tires. Please read the directions carefully and only use a mild detergent that is tire safe. Keeping the pressure at the recommended rating will also give you better mileage, handling and lower wear. All of these factors will give you longer tire life and a safe, memorable riding experience.

Be safe out there!

By Dave Miller