What Do The Numbers On Tires Mean?

by | Jan 30, 2018 | Trusted Auto Pros

What do the numbers on the side of your tires mean?

The number and/or letters on the side of your tire, essential mean size, but there are factors to consider too.

Why you should know the numbers on your tires

Unless you are upgrading or changing the rims on your vehicle you should always try to stay with the same size tire as what came with the vehicle from the factory. Whilst you may take it to a tire technician to replace them and he will know what the numbers mean, you may end up in a situation one day where you need to know what you are looking at. It’s always useful when price matching or shopping around too. You won’t be able to get an accurate price without knowing the size.

The first three numbers represent the tire width. This number would something like, ‘215’ or on our diagram it is 275 which quite a wide tire. This is the measurement from the outside (facing the world) of the tire to the inside of the tire (facing the inside wheel arch of your vehicle). A tire with 215 written as the first three digits, means the tire is 215mm wide.

There will be a forward slash (/) to separate the next numbers. Two numbers that follow the forward slash represent the profile of the tire, or also known as the aspect ratio. This is a two digit number that is a measurement of the height of the cross-section of the tire to its width. The lower this number, the more your tires will look like rubber bands. The higher this number, they will look more towards a tractor tire. This number is usually somewhere from 35 to 90. Somewhere around 60 is about average. These numbers will end in 0 or 5.

  • Next will be a letter or two letters that describe the construction of the tire. This is most always an ‘R’ for passenger type vehicles, which means radial. In our picture, there are the letters ‘ZR’ which means the tire is a performance radial for high speeds.
  • The last two digits will be the rim size. So in our pic, ’20’, is at the end. This means the rim size is 20″.

The rest of the numbers/letters spread around the tire represent some other important information such as;

  1. Load rating
  2. Speed rating
  3. DOT symbol
  4. TIN
  5. UTQG
  6. Traction grades
  7. Temperature grades

 

To find out more about tires or talk to someone about the tires on your vehicle, contact us here.