A tire’s sidewall is simply the outer and inner “walls” on the sides of a tire. Every sidewall has its own unique information that is divided into three main sections:
1. Tire Specs
This describes the fundamental characteristics of your tire. Size, construction, speed rating and more.
Tire Type
This designates the type of vehicle the tire fits. P is for passenger metric. Other letters are LT (light truck), T (temporary spare) and ST (special trailers).
2. Department of Transportation Safety Code
This assures that your tire complies with all Department of Transportation (DOT) safety standards. After the DOT insignia is your tire’s identification number, which begins with the tire’s manufacturer and plant code where the tire was manufactured. The ninth and tenth characters tell the week the tire was manufactured. The final number(s) signifies the year the tire was manufactured.
On the sidewall of your tire, you’ll find a code that tells the tire’s size and capabilities. Here’s a sample code:
P195/60R16 63H M+S
P – Type of tire
195 – Width of the tire across the tread in millimeters
60 – Aspect ratio of the sidewall compared to the width
R – Radial construction
16 – Diameter of the rim in inches
63 – Tire’s load rating
H – Tire’s speed rating
M+S – Tire is suitable for all-season driving
If the tire-size code starts with LT instead of P, it means the tire is a light-truck tire. Light-truck tires are designed to have higher-load carrying capacities and are usually found on pickups and SUVs. These vehicles are not required to have LT tires, and in many cases, the original-equipment specification calls for passenger-car tires.
3. Icons
Some tires have unique benefits, as showcased with specific icons.
The letters M and S (M +S) indicate that the tire meets the Rubber Manufacturers Association’s standards for a mud and snow tire. The letters can be found in the following combinations: M+S, M/S, and M&S. All-season tires carry this mark.
4. UTQG Code
The Uniform Tire Quality Grading (UTQG) was established by the National Highway Traffic Safety Administration (NHTSA) to test tires following government prescribed test methods and then grade each tire on three main components:
Treadwear: This is the wear rate of the tire, comparable only to other tires within a tire manufacturer’s line. 100 is the baseline grade. Therefore a tire with 200 would theoretically last twice as long on the government’s course compared to a tire with 100.
Traction: Traction grades are AA, A, B and C (with AA being the highest grade). They represent the tire’s ability to stop straight on wet pavement as measure on a specified government track. Any tire rated under C is considered unacceptable for road travel.
Temperature: The temperature grades, from highest to lowest, are A, B and C. These represent the tire’s ability to dissipate heat under controlled indoor test conditions. Any tire rated below C is considered unacceptable.