Automobile Maintenance Mandy purchased two new steel-belted all-weather radial tires for h...

Automobile Maintenance Mandy purchased two new steel-belted all-weather radial tires for her car. The tread depth on the new tires measures of an inch. The dealer told her that when the tires have worn down and their tread depth measures of an inch, she should replace the worn tires with new ones. How much will the tread depth decrease over the useful life of the tire?