A tire's size is typically listed on its sidewall. Here's an example: P205/55R16. The letter P stands for passenger car, then the number 205 is the measurement of the width of the tire in millimeters.
That's for size 215/55R16 tires that have a 50,000-mile tread life warranty. Compare that to Costco's best deal in the same size, the BFGoodrich Advantage Control, with a 75,000-mile tread warranty.
1. Calculated from an internal study using 205/55R16 winter tires on a prototype vehicle in a dry track environment, where the stopping distance of the vehicle driving at 80 km/hr with a tuned ABS ...
John Cooper Works entry strips (w/205 Transmission steering wheel paddle shifters) 16" x 6.5" 4-hole spoke alloy wheels, P195/55R16 tires, white turn-signal lights, front fog lights, sport seats ...