275 70 18 Tires? What Do All Those Numbers Mean?

Buying tires for your car, SUV, or truck means facing information that’s delivered in codes. Codes such as 275 x 70 x 18 tire size are meant to help you find the tire you need, but if you don’t know what they mean, they dont help you much. This guide provides the information you need to decipher tire codes.

Finding the tires you need

The first source of information to consult is your car’s manual. If you don’t have the manual, look for a number like 275 x 70 x 18 or 275 70r18 on your tires. The Compatibility Checker on eBay can help you determine which tires fit your vehicle. Your vehicle information is saved when you use the Compatibility Checker, so you can then use eBay’s My Garage to find any type of compatible parts for your vehicles, including tires.

What does a string of numbers like 275 70r18 mean?

A letter or letters before the first number stands for the type of vehicle the tire fits. A “P” stands for a passenger vehicle. “LT” is for a light truck. “T” is for temporary or spare tires.

The first number gives the tire’s width in millimeters, and the second is the tire’s aspect ratio — a percentage representing how wide the tire is in comparison to its height. The width of an LT275 70r18 tire is 70% of its height. The higher the aspect ratio the wider the sidewall.

A “B” between the second and third number means that the tire is a belted tire. An “R” means it’s a radial tire. A “D” indicates diagonal construction.

The third number provides the diameter of the wheel the tire fits. A tire with the number 275 70r18 in inches fits an 18-inch wheel. A fourth number represents the tire’s speed rating.

What are the different types of tires?

Tires manufactured for specific uses and weather conditions, such as a 275 x 70 x 18 mud tires or 275 x 70 x 18 snow tires, include the following:

  • Highway tires – These are for driving SUVs and trucks over long distances on smooth pavement.
  • Performance tires – These are for handling with less attention to comfortable rides.
  • Touring tires – These are for responsive handling at higher speeds.
  • M/T or mud-terrain tires – These are for driving in soft terrain like sand or mud.
  • A/T or all-terrain tires – These are for off-road driving and severe weather.
  • Temporary tires – These are for temporary use in case of a flat tire (compact tires should never be driven at speeds above 50 mph and should only be used for short periods of time).
  • Summer tires – These are for warm weather in either dry or wet conditions.
  • Winter tires or snow tires – These are for traction at temperatures below 45°F; can have studs for traction on icy roads.
  • All season tires – These are for good handling and comfortable rides with all road conditions,
  • All weather tires – These are for worse weather conditions than all-season tires.