How to Determine Overall Tire Diameter to Choose a Spare Tire Cover

Updated 08/09/2016 | Published 08/08/2016

Question:

Is there a chart for tire sizes to match the right cover size? I think my tire size is 225/75/15? Not at home to look.

asked by: Pete

Expert Reply:

Basically you can use the tire size to determine the best cover for it. Take the width, 225 (which is in millimeters) and multiply by 0.0394 to convert it to inches; 8.865.

Then multiply that by the aspect ratio, which in this case is 75 but it is a percent so you would multiply 8.865 by 0.75; 6.64875.

Then you will always multiply the result by 2 so 6.64875 x 2 = 13.2975.

Finally, add the wheel diameter; in this case 15 so 13.2975 + 15 = 28.2975. This is the overall height of the tire (give or take a fraction of an inch). Cover # 052963751406 fits 28 to 29 inch tire diameters and would work for you.

expert reply by: Michael H