How to Read a Tire

PDF download Download Article
PDF download Download Article

Knowing how to read a tire can give you important information about the type of tire on your car, RV, trailer, or motorcycle. This can be useful when buying replacements for your vehicle, considering tire upgrades, or changing to seasonal tires if you live where winter weather can be an issue. By knowing how to interpret the numbers and letters on a car tire, you can know the speed rating, temperature resistance, load index numbers, as well as the tire's width and rim diameter.

Get Car Support Solve Any Problem

wH
Hi there! Do you have a question about how to diagnose or fix a problem with your car? I’ve read the manual so you don’t have to. Select your make, model, and year, then ask away!
*
*
1

Read the manufacturer and the tire name.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    They say the name brand of the company, such as Hankook, or Michelin, or Goodyear.
    • The tire name may be letters only or a combination of numbers and letters, such as Goodyear's Eagle F1 GS-D3, the Hankook Ventus R-S2 Z212, or the Kumho Ecsta MX.
    2. Advertisement
2

Look at the service description.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    If it is on the tire you're looking at, it will usually be right after the manufacturer name. It comes in either a "P," "LT," "ST," or "T."
    • "P" stands for passenger car.
    • "LT" stands for light truck.
    • "ST" stands for special trailer.
    • "T" stands for temporary, and is borne by spare tires.
    • "BP" stands for cosmetically blemished passenger.
3

Find the width and aspect ratio.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    The series of numerals and letters will have a forward slash dividing them and have the general form of www/aaCrr.
    • The first series of three numbers tells you the width of the tire tread in millimeters. Width tread may range from 155 to 315.
    • The two numbers after the slash show the aspect ratio of the tire. This is the tread-width percentage that is equal to the sidewall's height. The average ranges from 55 to 75 percent in most passenger vehicles.
    2. Advertisement
4

Know the internal construction of the tire.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    "R" stands for radial construction, an industry standard for passenger cars. Some trucks may have a "B" instead, which stands for bias-ply, but which has largely been discontinued due to poor handling issues. [1]
5

Know the rim diameter.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    So, for example, if you have 22 inch (55.9 cm) rims, you'll have a tire whose rim diameter is also 22 inches (55.9 cm).
    • The letters in the position of SC or C signify the speed rating of the tire (pre-1991) or the construction of the tire. An "R" means the tire is of radial construction. If there is an "HR," this is a high-speed radial tire.
    2. Advertisement
6

Find the tire's load index.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    The load index is the tire size's relative load carrying capabilities. The higher the load index number, the larger load carrying capacity.
    • The index is not a hard number; it's just a symbol of sorts. To find out how many pounds a tire can carry, consult a Load-Carrying Capacity Per Tire chart.
    • To find out how much your entire car can carry without putting undue strain on your tires, multiply the number you found in the Load-Carrying Capacity Per Tire chart by four. You have four tires, after all.
    • Never replace your tires with ones that have a lower load index than the original tires. You always want to have tires with the same, or higher load index. So, if you had tires with a load index of 92 to start off, you want tires with at least an index of 92 or higher.
7

Find the tire's speed rating.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    The most common speed ratings are S, T, U, H, V, Z, W, Y, and (Y).
    • S means a tire can travel 112 mph (180 km/h) for extended periods.
    • T means a tire can travel 118 mph (190 km/h) for extended periods.
    • U means a tire can travel 124 mph (200 km/h) for extended periods.
    • H means a tire can travel 130 mph (210 km/h) for extended periods.
    • V means a tire can travel 149 mph (240 km/h) for extended periods.
    • Z means a tire can travel over 149 mph (240 km/h) for extended periods.
    • W means a tire can travel 168 mph (270 km/h) for extended periods.
    • Y means a tire can travel 186 mph (299 km/h) for extended periods.
    • (Y) means a tire can travel over 186 mph (299 km/h) for extended periods.
    2. Advertisement
8

Find the temperature-resistance rating.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    This may be an A, B, or C rating with A being the highest resistance and C being the lowest.
9

Find the Department of Transportation code.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    To do this, find the numbers that follow the DOT acronym.
    2. Advertisement
10

Find the cold inflation numbers.

PDF download Download Article
  1. Watermark wikiHow to Read a Tire
    This tells you the pressure the tire should be at to optimize tire performance.

Expert Q&A

Ask a Question
200 characters left
Include your email address to get a message when this question is answered.
Submit
      Advertisement

      Tips

      • If you're having difficulty to determine the meaning of the numbers on a tire, refer to your vehicle's owner's manual to discover the type of tires recommended for your vehicle.
        Thanks
        Helpful 0 Not Helpful 0


      Submit a Tip
      All tip submissions are carefully reviewed before being published
      Name
      Please provide your name and last initial
      Submit
      Thanks for submitting a tip for review!
      Advertisement

      You Might Also Like

      How to
      Register a Utility Trailer
      How to
      Install Snow Chains on Tires
      How to
      Put a Spare Tire on Your Vehicle: 11 Simple Steps
      How to
      Loosen Lug Nuts
      How to
      Let Air Out of a Tire
      How to
      Change Wheel Bearings
      How to
      Remove a Stuck Wheel & Prevent It From Happening Again
      How to
      Check Tire Tread with a Penny
      How to
      Put Tires on Rims
      How to
      Cut a Tire
      How to
      Replace Tie Rod Ends
      How Old Are Your Tires? Reading the DOT Code & Replacing Old Tires
      How to
      Measure Rims
      Air Pressure Draining from Your Tires? Here’s What It Means and How to Fix It
      Advertisement

      References

      1. ↑ https://www.edmunds.com/how-to/how-to-read-your-tire.html

      About This Article

      Article Summary X

      To read a tire, look for the width and aspect ratio, which is a series of numbers and letters that looks something like "225/50R17." The first 3 numbers are the width of your tire tread, and the second 2 numbers are the thread-width percentage. The letter indicates how your tire was constructed, with "R" standing for radial construction and "B" standing for biasply. The final 2 numbers are the rim diameter in inches. For more advice from our Mechanic co-author, like how to determine your tire's speed rating, scroll down!

      Did this summary help you?
      In other languages
      Thanks to all authors for creating a page that has been read 66,061 times.

      Reader Success Stories

      • Michael French

        Apr 20, 2022

        "Very informative, quick read and easy to understand. Learn something new every day."
      More reader stories Hide reader stories
      Share your story

      Did this article help you?

      Advertisement