The sidewall description on the tire "89H" is referred to as the tire's service description. The "89" is the load index and the "H" is the speed symbol.

The load index is an assigned number that corresponds with the load-carrying capacity of the tire. In this case, the "89" indicates a load-carrying capacity of 1279 lb at maximum inflation pressure. The load index for most passenger car tires ranges from 75-100.

Speed ratings are determined by indoor laboratory testing methods which measure high speed tire durability under controlled test conditions. These test procedures do not take into account underinflation, tire damage, vehicle characteristics or road conditions which can lead to sudden tire failure or loss of vehicle control at much lower speeds than indicated by the tire's speed rating.

When a "ZR" appears in the size designation (275/40 ZR17 93Y) the maximum speed is indicated by the service description - in this case 270km/h(186 mph).

Have you ever wondered why you need a tire speed rated for 270km/h(186 mph) when you never drive over 105km/h(65 mph)?

When replacing tires on your vehicle, you should use replacement tires with a speed rating equal to or greater than that of the original equipment tires if the speed capability and handling characteristics of the vehicle are to be maintained.

Please remember, never operate your vehicle in an unsafe or unlawful manner. Your Toyo Tires’ distributor or dealer can provide you with more information on speed ratings.

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The "15" indicates the diameter of the wheel in inches. You can learn more about changing the diameter of the wheels of your car in the Plus Sizing section.

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Passenger Tires

The "P" stands for "passenger" tire.

The "R" stands for "radial," indicating the tire has radial construction.

Other letters include "B" for belted bias construction or "D" for diagonal bias construction.

Light Truck Tires

The "LT" stands for "light truck."

The "M+S" indicates that the tire is designed for mud and snow applications. The Mud and Snow designation may also appear as "M&S" or "M/S."

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The width of a tire is referred to as its section width. This is the width of an inflated tire in millimeters at its widest point from sidewall to sidewall. The section height of the tire is measured in millimeters as well. It is approximately the distance from the rim to the tread surface of the tire when it is not carrying any weight.

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The letters "DOT" certify compliance with all applicable safety standards established by the Department of Transportation (DOT). Beside this is a tire identification or serial number. This serial number is a code with up to 11 digits that are a combination of numbers and letters.

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Uniform Tire Quality Grading

The Uniform Tire Quality Grading System, or UTQG, is a system developed by the government designed to provide consumers with information on tire treadwear, traction, and operating temperature range.

Treadwear Rating

The treadwear grade is a comparative numerical rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course. For example, a tire graded 150 would wear 1 1/2 times as well on the course as a tire graded 100. The relative performance of a tire depends upon the actual conditions of its use which may depart significantly from the test conditions due to variations in driving habits, service practices, and differences in road characteristics and climates.

Traction Rating

The UTQG Traction Rating indicates the tire's ability to stop a vehicle moving straight forward on wet pavement. The ratings are AA, A, B, and C, with AA being the best.

Temperature Rating

The UTQG Temperature Rating indicates the tire's ability to effectively dissipate heat. The ratings range from A to C, with A being the best.

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