Tire basics

Used tires vs new tires

A used tire can be a good value when it has enough tread, no cuts, bulges, or badly placed patches, and a reasonable age. A new tire has full tread and a known history. The right choice depends on how many miles you drive, the weather where you live, and your budget.

Tread depth

Tread depth is measured in 32nds of an inch. A new passenger tire usually starts around 10/32 to 11/32. The legal minimum in most US states is 2/32. A simple check is the penny test: if you can see all of Lincoln's head when a penny is in the groove, the tread is likely at or below 2/32.

Many drivers replace tires earlier, around 4/32, because wet braking gets worse as tread wears down.

Tire age

Tires age even when they sit unused. Find the DOT code on the sidewall; the last four digits show the week and year of manufacture. Many manufacturers and safety groups suggest replacing tires after about six years, regardless of tread.

Signs a tire needs attention

Look for uneven wear across the tread, cracks in the sidewall, bulges, cuts that reach the cords, and vibration at speed. Any of these means a visit to a tire shop is a good idea.