As a general rule, people should buy new tires for every 40,000 miles driven, although the number varies depending on factors including the condition of the original tires and which road surfaces were used, according to Autos.com. Tire rotation every 5,000 to 10,000 miles helps keep tires in good shape.
Some car makers recommend that drivers wait no longer than six years to buy new tires for their cars, according to Edmunds. The principle holds regardless of the tires' tread wear. Other manufacturers say a tire can remain good for as long as 10 years but that annual inspections should be conducted after year five.