Steering & Suspension: Wheels & Tires: Tire construction
This Video Sequence is
not available in the free
CDX eTextbook
 
Click this icon for more information about CDX Automotive Resource Kit Plus
This Knowledge Check is
not available in the free
CDX eTextbook
 
Click this icon for more information about CDX Automotive Resource Kit Plus
This Lab Experiment is
not available in the free
CDX eTextbook
 
Click this icon for more information about CDX Automotive Resource Kit Plus
This Workshop Activity Sheet is not available in the free CDX eTextbook
 
Click this icon for more information about CDX Automotive Resource Kit Plus
This Assessment Checklist is not available in the free CDX eTextbook
 
Click this icon for more information about CDX Automotive Resource Kit Plus
This Handout Activity Sheet is not available in the free CDX eTextbook
 
Click this icon for more information about CDX Automotive Resource Kit Plus

Topic IntroductionHelp

Tire ratings for temperature & traction

Summary
A Uniform Tire Quality Grading or UTQG grade provides information on tread wear, traction and temperature.

One of the markings on the sidewall of a tire is a Uniform Tire Quality Grading or UTQG grade.

The tire's UTQG rating provides information on three aspects of the tires durability and operational characteristics.
They are:

The tread wear number comes from testing the tire in controlled conditions. The higher the number, the longer the life expectancy of the tread.

Since no one vehicle will be subjected to exactly the same surfaces and at the same speeds as the controlled conditions, the number can only be an indicator of expected tread life in 'normal conditions'.

The rating is based on a percentage of the projected wear life. For instance, a tire rated at 400 has a projected life twice that of a tire rated at 200.

There are many factors that influence wear, such as vehicle speed, road surface, climate, vehicle wheel alignment, and the driving characteristics of the driver. As such the rating can only be an indication of the anticipated wear characteristics of the tire in controlled conditions.

A traction rating is a letter based indicator system. The rating is based on the tire's ability to stop a vehicle on wet concrete and asphalt in a straight-line situation. It does not indicate the tire's cornering ability.

The Tire traction indicators are rated as AA, A, B or C. AA is the highest rating.

It is important to note that the test and relevant rating does not indicate hydroplaning resistance, dry or snow traction capacity, or cornering capability in wet, dry or snow conditions.

The Temperature rating of a tire is a letter based on a controlled step speed test. The possible ratings are A, B, and C. The rating is a measure of how well the tire dissipates heat and how well it handles the buildup of heat. Excessive heat buildup can reduce tire life, or even lead to tire failure. However, while temperature plays a role in the speed capability of a tire, it is not the only factor.

It is important to remember that these ratings are based on standardized test conditions, and the tests do not reflect tires that are operated in overloaded, under inflated, and/or misaligned conditions. It should also be noted that when rated one tire might be a low "A" and another a high "B", so the actual operating performance differences might be relatively small.

It is not uncommon for there to be differences in UTQG ratings within a given tire design. Sometimes a particular vehicle manufacturer will require certain properties for the tires supplied to their vehicles, which can affect the ratings, both positively and negatively.

Sometimes there are differences between small sizes and large sizes of tires in a given design. All of these aspects can affect the actual rating that is put on the sidewall.