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Click Here to Find More Detailed Information About Tyres in our FAQ Section
Tyres are more than just black and round… They utilize an innovative mix of chemistry, physics and engineering. And we’re here to help explain. Learn how to read your sidewall, understand tyre construction and speed ratings, and find the right tyres for your car.
Reading a Tyre Side Wall
The numbers and letters on the side of your tyre have very specific meanings.
Click here to know what they mean.
The Right Tyre For Your Car
Your correct tyre size and tyre pressure can be found in your vehicle’s owners’ manual in the glove compartment or on the OEM sticker on your driver’s side door.
Click here to learn how to read this information.
Tyre Speed Ratings & Tread Life
The most common tyre speed ratings, speeds and vehicle usage are as follows:
The Origin of Speed Ratings
We can thank Germany's famous Autobahn for tyre speed ratings. Tyre speed ratings range from A (the lowest) to Y (the highest). But the chart is not completely in alphabetical order. For example, H is between U and V, with the common perception that H stood for "high performance" at one time. As manufacturers continue to add speed to their vehicles, tyre speed ratings evolve to match the speeds. For example, Z was the highest rated speed at 149+ until W & Y were used to match the higher speeds of exotic sports cars.
Speed Ratings Refer to More Than Just Speed
Speed ratings make a difference not only in regards to speed, but in regards to ride comfort, wear and cornering ability. Typically, the higher the speed rating, the better the grip and stopping power, but the lower the tread life. You can always increase the speed rating of the tyres on your vehicle for improved performance, but can never decrease it without reducing the vehicle top speed to that of the lower speed rating selected.
Mixing Speed Ratings
If tyres of different speed ratings are mounted on a vehicle, the lower speed-rated tyres should be placed on the front axle regardless of which axle is driven. This is to prevent a potential oversteer condition. Vehicle handling may be affected, and the vehicle’s speed capacity is now limited to the lowest speed-rated tyre. For best performance, it is recommended that the same size and type of tyre be used on all four wheel positions.
235/55R17 99H- The load index (99) is the tyre size's assigned numerical value used to compare relative load carrying capabilities. The higher the tyre's load index number, the greater its load carrying capacity.
97 = 1,609 pounds/729 kilograms
98 = 1,653 pounds/749 kilograms
99 = 1,709 pounds/775 kilograms
A tyre with a higher load index than that of the Original Equipment tyre indicates an increase in load capacity. A tyre with a load index equal to that of the Original Equipment tyre indicates an equivalent load capacity. A tyre with a lower load index than the Original Equipment tyre indicates the tyre does not equal the load capacity of the original and should not be considered for installation on the vehicle.
Typically, the load indexes of the tyres used on passenger cars and light trucks range from 70 to 130.