MINIMIZING IRREGULAR TIRE WEAR

The right inflation pressure can minimize many types of irregular wear -- and that means higher removal mileage and reduced tire handling costs.

Bridgestone/Firestone has assembled data from its own research as well as studies done by The Maintenance Council (TMC) and Rubber Manufacturers' Association (RMA) that concludes that tires last longer when properly inflated.

Tires rotate about 500 times for every mile traveled, so in 100,000 miles every part of the tread gets pressed against the pavement some 50 million times. Since uneven, irregular wear is the result of uneven abrasion, tires need to press against the pavement the same way every single time. Having the tire maintain a consistent shape throughout its life helps a lot.

The way to achieve this "ideal" shape is to adjust inflation pressure after consulting load and inflation tables. TMC reports that 10 percent underinflation will shorten tread life by nine to 16 percent. If an average tire price of $250 is used, this underinflation costs about $25 per tire. Because tires will be changed more often, fleets will pay more in tire service fees along with costs related to downtime.

How many drivers and maintenance people, if they had a target inflation pressure of 100 psi, would consider 90 psi (10 percent under-inflated) "close enough?" TMC suggests that each 10 percent results in a similar loss of tread life. So 20 per-cent underinflation could cost $50 per tire. If underinflation exceeds 10 per-cent, there may be bigger problems such as flats and emergency road service calls that can cost anywhere from $100 to $1,000.

Both TMC and RMA recommend that tires found to be 20 percent or more under-inflated should be immediately removed from service, demounted and inspected for damage.