Subaru Ascent 2018-2026 Owner's Manual: Uniform tire quality grading standards
The Uniform Tire Quality Grading (UTQG) system provides valuable comparative information about tire performance, specifically in the areas of treadwear, traction, and temperature resistance. For Subaru Ascent owners, understanding these ratings can help in selecting the most suitable tires for safety, durability, and driving comfort.
These grading standards are designed to assist consumers in making informed purchasing decisions when choosing replacement tires for their Subaru Ascent, especially when comparing different brands and models.
The UTQG ratings are typically molded into the tire sidewall, located between the tread shoulder and the maximum section width, making them easily accessible for inspection.
For example:
TREADWEAR 200 TRACTION AA TEMPERATURE A
The grading system applies to new pneumatic tires intended for passenger vehicles such as the Subaru Ascent. However, it does not apply to specialized tire categories including deep-tread off-road tires, winter (snow) tires, compact spare tires, tires with rim diameters of 12 inches or less, or certain limited-production tire types.
In addition to UTQG ratings, all passenger car tires used on the Subaru Ascent must meet federal safety standards to ensure baseline levels of reliability and performance.
TREADWEAR
The treadwear grade represents a comparative rating that reflects how quickly a tire’s tread is expected to wear under controlled testing conditions on a standardized government test course.
For instance, a tire with a treadwear rating of 150 is expected to last one and a half times longer than a tire rated at 100 when tested under identical conditions.
It is important to note that real-world performance for Subaru Ascent tires may vary significantly depending on driving habits, road conditions, maintenance practices, and environmental factors such as climate.
TRACTION AA, A, B, C
Traction grades indicate a tire’s ability to stop on wet surfaces. The ratings range from highest to lowest as AA, A, B, and C.
These values are determined through standardized braking tests conducted on wet asphalt and concrete surfaces. Tires with higher traction grades generally provide better stopping performance for your Subaru Ascent under wet conditions.
A tire marked with a grade of C may exhibit reduced traction capabilities and should be selected with caution depending on driving conditions.
WARNING
The traction grade assigned to a tire is based solely on straight-line braking performance under controlled conditions. It does not account for acceleration, cornering ability, hydroplaning resistance, or peak grip levels of your Subaru Ascent.
TEMPERATURE A, B, C
The temperature grade reflects the tire’s resistance to heat generation and its ability to dissipate heat effectively during operation. Ratings are classified as A (highest), B, and C.
These grades are determined through laboratory testing on a controlled indoor test wheel. Tires with a higher temperature rating are better equipped to handle heat buildup, which is particularly important during high-speed driving or under heavy loads in your Subaru Ascent.
Maintaining tires with appropriate temperature ratings contributes to improved durability and reduces the risk of overheating-related failures, ensuring safer and more reliable performance of your Subaru Ascent in demanding conditions.
Prolonged exposure to elevated temperatures can significantly degrade the internal materials of a tire, reducing its overall lifespan and performance. In the Subaru Ascent, excessive heat buildup—especially during high-speed driving or under heavy loads—can weaken the tire structure and, in extreme cases, lead to sudden and dangerous tire failure.
A temperature grade of C indicates the minimum level of performance required for all passenger vehicle tires under Federal Motor Vehicle Safety Standard No. 109. Tires installed on your Subaru Ascent must at least meet this baseline requirement to ensure basic operational safety.
Temperature grades B and A represent progressively higher levels of heat resistance and durability. Tires with these ratings are better suited for demanding conditions, offering improved resistance to heat buildup during extended driving or when carrying heavier loads in your Subaru Ascent.
WARNING
The temperature rating assigned to a tire is based on proper inflation and normal loading conditions. Driving your Subaru Ascent with underinflated tires, excessive load, or at high speeds—whether individually or in combination—can result in rapid heat buildup and significantly increase the risk of tire failure.
Reporting safety defects (U.S.A.)
If you believe that your Subaru Ascent has a defect that could compromise safety, potentially leading to an accident, injury, or even loss of life, it is essential to take immediate action. You should report the issue both to Subaru of America, Inc. and to the National Highway Traffic Safety Administration (NHTSA).
When NHTSA receives multiple reports of similar issues, it may initiate an investigation. If a widespread safety defect is confirmed, NHTSA has the authority to mandate a recall and require corrective actions. However, it does not intervene in individual disputes between vehicle owners, dealerships, or manufacturers.
To contact NHTSA, you may call the Vehicle Safety Hotline toll-free at 1-888-327-4236 (TTY: 1-800-424-9153), visit the official website at http://www.safercar.gov, or write to: Administrator, NHTSA, 1200 New Jersey Avenue, SE, West Building, Washington, DC 20590. Additional vehicle safety information is also available online.
How to contact Transport Canada in order to report a safety concern relating to the vehicle (Canada)
Staying informed about tire temperature ratings and promptly reporting potential safety concerns ensures that your Subaru Ascent remains reliable, safe, and compliant with all applicable safety standards across different driving conditions.