The manufacturer's size recomendation is found on the placard in the driver side doorjamb. The placard will look similar to the one here.

If you are not sure what tire size is installed on your vehicle, please check your size, and look for the following:

Please note that the proper Original Equipment (O.E.) tire size for the vehicle is determined by the vehicle manufacturer. At 1010TIRES.COM we base the Original Equipment sizes on the best information currently available to us. Options or changes by the manufacturer may change the Original Equipment size on your vehicle. 1010TIRES.COM always recommends that, before making a purchase, you verify that the size listed on our Tire search matches the tire size listed on your vehicle. You can find the manufacturer’s recommendation on your vehicle, located in the driver’s side door jamb, or in your vehicle Owner’s Manual.