BY BEN L. KAUFMAN
The Cincinnati Enquirer
Ohio drivers who send vehicles through E-check with under-inflated tires increase their chance of tire failure once they're back on the road, industry and E-check spokesmen say.
During E-check tests, drive wheels nestle between two rollers on a machine called a dynanometer.
Those rollers spin the drive wheels and simulate various road speeds during the biennial emissions test.
What happens next was explained by Steven Butcher, vice president for technology and standards at the Rubber Manufacturers Association in Washington, D.C.:
The faster any wheel turns, the hotter a tire gets. Heat is the enemy of tire life, and under-inflation and overloading increase excess heat. Deflection -- where a tire loses its round shape -- also increases heat. A tire is made to deflect in one spot, "where the rubber hits the road."
Two rollers cause a tire to deflect twice and increase stress; stress creates heat, and two rollers are worse than one, and a test that runs drive wheels 15-20 minutes would be worrisome.
"There could be some problems with a substantially under-inflated tire," Mr. Butcher said. "It could fail."
Failure means some of the many layers of tire material come apart. That's likeliest when heat approaches the temperature at which the manufacturer cured the rubber in the tire, said Tony Michel, owner of Michel Tire Co.
He agreed with Mr. Butcher that tire failure from heat-induced delamination is rare, but he said under-inflation is chronic. Ohio's E-check program, which requires tailpipe testing for most cars and light trucks, tests vehicles at 13 southwest Ohio stations run by MARTA Inc.
MARTA technicians do not check tire pressures.
Instead, they turn away any vehicle with wildly under-inflated tires, MARTA regional manager Edward Lemmert said.
That, however, presents customer relations problems because modern tires "look like they're low all of the time, and they're not."
MARTA's 53 test lanes, not stations a full E-check spins twin rollers up to four minutes -- and only part of that would be at the top speeds of 52-53 mph, Mr. Lemmert said. If his employees were to test tires on every vehicle, it would create delays, Mr. Lemmert said, adding five minutes to the ideal of 15-20 minutes for the entire E-check.
