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CAA's ultimate tire buying guide.

Jordan March 01, 2015
Close up image of two tires
Though they’re one of the most visible and well-recognized parts of any vehicle, replacing a car’s tires can be confusing. Numerous factors can affect their lifespan, including how they’re used, your style of driving, the type of vehicle you own, where you drive and even your vehicle’s overall maintenance. Their size needs to be considered as well; putting an undersized tire on your car can overheat or overload it, while oversized tires can rub parts of the vehicle causing potentially hazardous complications.

Looking for a quick way to find out what tire you should use? Check your vehicle owner’s manual or the label inside the glove box. Can’t find the owner’s manual? Call or visit the vehicle manufacturer or dealership for help. But remember: just because a tire is suited for your vehicle doesn’t necessarily make it the best choice. Here are a few tips to keep in mind when looking for a new set.

How to read a tire’s sidewall.

Sidewalls – as the name implies – are located on the side of your tire, close to the rim. They’ll tell you the basic details of any tire including their size and what season they’re suited for. Refer to them to make sure what you’re buying is exactly what you need. Below is a diagram and accompanying explanations for the possible symbols you’ll find.

A reference image of sample tire markings.
  1. The peaked mountain with snowflake indicates it’s a snow tire
  2. M + S (mud and snow) indicate an all-season tire
  3. P stands for passenger vehicle. L means light-duty vehicle
  4. 195 is the width of the tire in millimeters
  5. 60 is the aspect ratio (the percentage ratio of the height of the sidewall to the width)
  6. R means the tire has radial construction
  7. 15 represents the wheel diameter in inches
  8. 87 is the load index
  9. Q indicates the speed rating (can be any letter between M-Z)

The Uniform Tire Quality Grading (UTQG) system provides useful information on tread wear, traction and temperature. The ratings are based on standard tire tests under controlled conditions. All tires for sale in North America have their grades branded on the sidewall. The grade designations are used for comparison purposes only between tires.

Common tire terms.

Tread wear: The tread wear is a comparative rating based on the wear of the tire, when tested in a controlled environment. For example, a tire graded 400 wears two times as well as a tire graded 200. Grades range from 50 to more than 600, increasing in 20-point increments. The actual life and performance of a tire depends upon the conditions of its use.

Traction: Grades indicate the measurement of a tire’s ability to stop a car in a straight-ahead motion on a wet test surface pavement. Traction ratings are assigned to the tires tested, and range from AA (highest) to C (lowest). Tests are performed only for straight-ahead sliding and do not apply to cornering traction acceleration.

Temperature: Grades range from A (highest) to C and represent a tire’s resistance to heat and its ability to dissipate heat under controlled conditions. Tires that receive a “C” grade meet minimum performance standards. The higher the grade, the better the performance. Grades are based on tires that are properly inflated and not overloaded.


Overwhelmed by too many options? Find out what the experts are saying:

National Highway Traffic Safety Administration – Features up-to-date tire ratings.

Transport Canada and Be Tire Smart – For helpful information on tire maintenance and driving, plus great tutorials on how to properly inflate your tires, check pressure and when and how to rotate them.

Proper tire and overall vehicle maintenance is critical to the safe operation of your vehicle. It will also help improve your fuel efficiency, extend the life of your tires and provide better vehicle handling. When looking for tires, always use a reputable dealer. Visit your local Approved Auto Repair Services (AARS) facility for more information.