What do the numbers on my tire mean?

The numbers on your tire sidewall can seem like gibberish at first glance. The standard format includes three sets of digits that represent (in order) the width of the tire in millimeters, the aspect ratio (the height of the sidewall as a percentage of its width), and finally, the diameter of the wheel it fits on in inches.

How do I choose new tires based on these measurements?

Determining which measurements are compatible with your car depends primarily on two things: what type(s) of driving you'll be doing most often and how much clearance there is between moving parts like suspension components.

Can I change my tire size without consulting a professional?

Changing your vehicle's tire sizing can potentially offer advantages such as better off-road ability, but it must be executed with caution. Altering the aspect ratio - changing from our car example of 70 to 75 or vice versa - will adjust height vs width significantly enough so that accuracy displayed on you dash mounted speedometer may factor wrong velocities achieved…