Tire Guide and Tips: Understanding your Tires

What’s On Your Tire’s Sidewall?

This is where the information on your tires can be found. With a little explanation, it is pretty easy to understand what all the letters and numbers mean on your tire’s sidewall. These numbers are indicators of the size, type, and performance of your vehicle’s tire.

For example, the number may read P225/70-R15, 89H:

  • P – This stands for Passenger Tire (LT would stand for Light Truck)
  • 225 – This is the width of your tire in millimeters from sidewall to sidewall
  • 70 – This is the Aspect Ratio or Sidewall height (distance from rim to tread) as a percentage of the tread width
  • R – Tire construction (it references the layers that run radially across the tire), this one is Radial (B would be Belted Bias and D would be Diagonal Bias)
  • 15 – This Represents the size of the wheel in inches from one end to the other, it tells us the size of the wheel that the tire is intended to fit
  • 89H – this is the load index; it indicates the maximum load that your tire can support when it is properly inflated
  • Speed rating – sometimes this is put in front of the R/B/D
    • A straight R rating means that it is rated for speeds of up to 100mph
    • S rated is for speeds up to 112mph
    • T rated is for speeds up to 118mph
    • U rated is for speeds up to 124mph
    • H rated is for speeds up to 130mph
    • V rated is for speeds up to 149mph
    • Z rated tire is for speeds in excess of 149mph
  • Tread rating – this is written in small letters on the sidewall of your tire, the higher the number, the longer it should last. 100 is the basic tread wear rating.
  • Traction rating – this works just like a grading system with ‘A’ being the best, ‘B’ is good, and ‘C’ is acceptable. This number is also found on the sidewall.
  • Temperature rating – this works like a grading system as well with ‘A’ best, ‘B’ good, and ‘C’ acceptable. If you drive your car very hard, you want a temperature rating of ‘A’ because a ‘C’ would fail faster under these conditions. This number is also on the sidewall.

The good thing is you don’t need to remember all of this, you just need to have a great auto technician to take your vehicle to and they understand what this all means and will take care of things for you.