Many people ignore tires as long as they aren’t flat. Here are some facts to help tires stay round:
1. Tires exposed to the sun during long-term storage often develop a dusty brown coating. “We put chemicals in tires that reduce damage from exposure to sunlight and ozone,” says Greg Jones, with Firestone Agricultural. “That brownish coating is those chemicals coming to the surface, helping protect the tire. It’s actually better to leave that coating on the surface than to wipe it off. But we can only put so much of those protectants in the rubber. Eventually they get used up, and that’s when tires get hard and start to weather check.”
2. Tire “protectants/preservatives” are, for the most part, cosmetic. “I’ve never seen any product that actually soaks into the rubber enough to make a difference,” says Jeff Miller, with Trelleborg Wheel Systems. “Rubber doesn’t absorb anything well. Most products advertised as rubber preservatives just make tires look shiny and new.”
3. It’s normal for any tire to lose 2 psi of air pressure per month during storage. The slow leakage may be around or through a valve stem or from the bead area. Leave any tire unattended long enough and it will become under-inflated.
4. The biggest factor that influences the longevity of high-pressure semi-truck tires is air pressure. “Heat is the enemy of rubber,” says Miller. “Running a semi-truck tire even 5 psi lower than recommended creates excess heat in the tread and carcass that affects the tire’s life.”
5. In a report by tire re-treader Bandag, it was noted that “pinging” tires with a hammer or tire billy to check air pressure was as accurate as, “…checking the engine oil level by tapping the side of the oil pan.” Bandag recommends using an accurate air pressure gauge to keep tires within 2 psi of recommended pressure.
