What Tire Size Do I Need for My Car?

Misc - Check Tire Pressure

If you’re in the market for a new tires, the first thing you need to do is find out what size tire you need. And don’t just glance at it and say “Looks like medium-size to me.” Just kidding. Fortunately, it’s not all that difficult to do and there are several ways you can find out exactly what tire size you need without taking random stabs in the dark.

  • Read the sidewall of the tire itself. Unless your tire’s been destroyed by a run-flat or a blowout, you should be able to read the brand and size of your tire right on its exterior sidewall. But sometimes these numbers can be a bit obscured by time and road gunk, and the fact that this information is usually printed in black lettering may not help matters. See Technical Information below if you are interested in learning more about what a sidewall number represents.
  • Keep in mind, just because you can read the information on the tire sidewall, the tire(s) may or may not be the correct rated tire for your car. This is especially the case if the car had a previous owner or aftermarket rims were installed. Its best to thumb through your owner’s manual. If your car’s had replacement rims installed or has had any suspension work to make room for bigger tires, forget what the manual says.
  • If you haven’t had any after-market work done or the car was purchased used, but you no longer have your manual handy, you can find your original equipment tire size by swinging your driver’s side door open and reading the sticker that’s placed there when the car is manufactured. This will tell you your proper tire size, and even how much air you should be running in your tires for the smoothest drive.
  • If all else fails, you can determine what size tire you need simply by talking to an auto mechanic and asking them to look it up for you. Most auto shops will have this information in reference books or in their computer system. All you need to provide them with is the year, make and model of your car and they’ll be able to point you in the right direction. Need a good mechanic, start with Openbay where you can compare pricing and book service from quality local shops with the click of a button.
UPDATE – two of our readers had good points to make regarding the code for month and year of manufacture and speed and load rating. Thank you Jay Barrett and Keith Zelazny.
Technical information: Important sidewall information includes the brand of tire (e.g. BF Goodrich, Bridgestone, Cooper, Dunlop, Firestone, Goodyear, Michelin, Pirelli, Toyo, Yokohama, etc.). The series and model of tire usually follows the brand. For example, Goodyear Eagle RS-A EMT. Next is the size and type of tire. For example purposes, let dissect the following:  P215/60R16 94V. The initial letter defines the tire type; P = passenger, LT = Light Truck. Next is the tire width measured in mm from sidewall to sidewall. In this example, the tire width is 215 mm. Next is the aspect ratio which is the ratio of the height of the tire’s cross-section to its width. In this example, 60 means the height is 60% of the tire’s width. Next is a letter that represents the construction of the tire. In this example, R=Radial. Rim diameter is next and it represents the width in inches or cm of the wheel from one end to the other. In this example, the diameter is 16 in. Next is the load index. This is an assigned number that corresponds with the maximum weight that a tire can support when properly inflated. Most passenger car tires load indexes range from 75 to 100. In this example, the load index corresponds to 1,477 lbs. And last is the letter which represents the speed rating of the tire. In this example, V=130+ miles per hour.