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There’s no doubt about it, tires are crucial to the overall safety and performance of your Volvo. Getting the right size tire for your Volvo, and keeping them properly maintained can affect on the starting, stopping, handling and efficiency of your Volvo. The first step in getting to know your tires is the determining the size. The following figures are examples of a tire designation:
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1. 215: the width of the tire (in millimeters) from sidewall edge to sidewall edge. The larger the number, the wider the tire.
2. 65: The ratio of the tire's height to its width.
3. R: Radial tire.
4. 15: The diameter of the wheel rim (in inches).
5. 95: The tire’s load index. In this example, a load index of 95 equals a maximum load of 1521 lbs (690 kg).
6. H: The tire's speed rating, or the maximum speed at which the tire is designed to be driven for extended periods of time, carrying a permissible load for the vehicle, and with correct inflation pressure. For example, H indicates a speed rating of 130 mph (210 km/h).
7. M+S or M/S = Mud and Snow,
AT = All Terrain, AS = All Season
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8. U.S. DOT Tire Identification Number (TIN): This begins with the letters "DOT" and indicates that the tire meets all federal standards. The next two numbers or letters are the plant code where it was manufactured, the next two are the tire size code and the last four numbers represent the week and year the tire was built. For example, the numbers 317 mean the 31st week of 1997. After 2000 the numbers go to four digits. For example, 2501 means the 25th week of 2001. The numbers in between are marketing codes used at the manufacturer's discretion. This information helps a tire manufacturer identify a tire for safety recall purposes.
9. Tire Ply Composition and Material Used: The number of plies indicates the number of layers of rubber-coated fabric in the tire tread and sidewall. Tire manufacturers also must indicate the ply materials in the tire and the sidewall, which include steel, nylon, polyester, and others.
10. Maximum Load: Indicates the maximum load in pounds and kilograms that can be carried by the tire. Refer to the vehicle's tire information placard or the safety certification label, located on the B-Pillar or the driver's door or on the inside of the fuel filler door on Canadian models, for the correct tire pressure for your vehicle.
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Treadwear, Traction, and Temperature grades:
Treadwear: The treadwear grade is a comparative 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 one and one half (1 1/2) times as well on the government course as a tire graded 100. The relative perofrmance of tires depends upon the actual conditions of their use, however, and many depart sinificantly from the norm due to variation in driving habits, maintenance practices and differences in road characteristics and climate.
Traction: The traction grades, from highest to lowest, are AA, A, B, and C, as measured under controlled conditions on specified government test surfaces of asphalt and concrete. A tire marked C may have poor traction performance. The traction grade assigned to this tire is based on braking (straight-ahead) traction tests and is not a measure of cornering (turning) traction.
Temperature: The temperature grades are AA (the highest), A, B, and C, representing the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the material of the tire to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The grade C corresponds to a minimum level of performance that all passenger vehicle tires must meet under the Federal Motor Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law. WARNING: the temperature grade for this tire is established for a tire that is properly inflated and not overloaded. Excessive speed, under inflation, or excessive loading, either seperately or in combination, can cause heat buildup and tire failure.
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12. Maximum permissible inflation pressure: The greatest amount of air pressure that should ever be put in the tire. This limit is set by the tire manufacturer. |
Watch for wear
Tires degrade over time, even when they are not being used. Heat caused by hot climates, frequent high loading conditions or Ultra Violet (U.V) exposure can accelerate the aging process. You should replace the spare tire when you replace the other road tires due to the aging of the spare. A tire's age can be determined by the DOT stamp on the sidewall (Refer to #8)
Tread Wear Indicator
The tires have wear indicator strips running across or parallel to the tread. The letters TWI are printed on the side of the tire. When approximately 1/16" (1.6 mm) is left on the tread, these strips become visible and indicate that the tire should be replaced. Tires with less than 1/16" (1.6 mm) tread offer very poor traction.
When replacing worn tires, it is recommended that the tire be identical in type (radial) and size as the one being replaced. Using a tire of the same make (manufacturer) will prevent alteration of the driving characteristics of the vehicle.
For more applicable information, please consult owner’s guide.
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