Feature Article: Seven tire killers
Seven tire killers
By John Baxter
A tire running on low air works “harder than it was intended to work. The tread rubber heats up,” says Guy Walenga, director of engineering for commercial products at Bridgestone/Firestone. Furthermore, the potential damage accelerates the further the tire gets from optimum pressure. For example, running 10 percent low means much more than a 10 percent increase in flexing, heat and damage from bending the steel cords beyond the point where they will spring back.
“You can never repair damage done to a tire this way,” Walenga says of overflexing. And “there is no tell-tale sign of damage. It may end up being useless for retreading.”
It also might be useless long before retreading. “Any commercial tire that has been run more than 20 percent underinflated must be considered flat and removed from the wheel to be inspected for damage,” says Matt Gudermuth, Continental Tire’s warranty manager for commercial vehicle tires. “Circumferential fatigue ruptures, known commonly as zipper failures, are caused by extreme deflection of steel casing cords during the load cycle of rotation, when the tire is underinflated or overloaded.”
2 Overinflation or overloading
Overinflation can happen in these ways, says Jones:
• You put a significant amount of extra air in the tire to compensate for leakage. It’s always better to fix the leak and inflate the tire up to the proper pressure.
• You air the tire up on a cold morning and end up driving at high speeds after the weather warms significantly. Take time to check pressure in this situation and adjust as necessary.
• You’ve aired your tires for 80,000-pound running and then start hauling lighter freight. Instead, reduce the pressure according to the manufacturer’s recommendations for the axle loading.
3. Poor wheel alignment
“If the tires are not rolling straight down the road and straight up on the road surface, they are going to wear faster or in some sort of uneven way,” says Goodyear Marketing Communications Manager Tim Miller. “Today’s radial tires are designed to run such long distances before they wear out, any issue with toe, camber, caster and all axle perpendicularity to the chassis centerline will have a marked, negative effect.”