A Guide to Tyre Load Index and Tyre Speed Rating
Meet the Tyre Contact Patch
The numbers and letters at the end of the sequence that you see on your sidewall correspond to what’s called the “tyre service description” — three or 4 figures that signify both the tyre load index and the tyre speed rating. The load index indicates how much weight a tyre can safely carry at the maximum air pressure, and the speed rating represents the maximum operating speed.
If you’re still confused, if you just need to find out your tyre speed rating or if you have no idea what the tyre load index or Z speed means, then you’re in the right place. We’re here to help you get a grasp on what those mysterious codes on your tyres mean, how much weight your tyres can carry and the maximum speed capability when the tyre is properly inflated.
Tyre Load Index
Want to find your tyre load index, also known as the load-carrying capacity? Locate the two or 3 digits at the end of your tyre size — the fancy, technical name for the long string of letters and numbers encircling your tyre — that precede the single letter.
For example, if you see “88S” at the end of the tyre size, the load index would be 88. So what does that mean for you? Generally speaking, the higher the tyre load index, the more weight the tyre can safely carry. In the case of a tyre with an 88 load index, that tyre would be able to support 560.18 kilogram at maximum air pressure. When you multiply that amount for a single tyre by four, your vehicle’s maximum load capacity would be 2240 kilos.
Tyre Speed Rating
To find your tyre speed rating to reference the single letter at the end of your tyre size — this will be where you’ll find the speed rating for all tyres manufactured since 1991.
The most common tyre speed ratings are L, M, N, P, Q, R, S, T, U, H, Y and (Y) — letters that designate speeds ranging from 75 to above 186 km per hour.
Unless you’re regularly driving on — or dreaming about driving on — the Autobahn in Germany, you may have never even heard of Z-speed tyres. Sound fast, don’t they? Well, that’s because they are. When they were first created, Z-speed tyres were meant to represent the highest tyre speed rating ever — speeds that exceeded 149 km per hour.
What you might not know is that, since Z-speed tyres were created, tyres with even higher tyre speed ratings have been introduced: enter the W-speed, Y-speed, and (Y) speed tyres. Tyres with speed ratings of W, Y, and (Y) can withstand the highest speeds, such as those you’d find when driving an exotic sports car, of 168 to 186 km per hour and above.
If you’ve ever wondered how old your tyres, it’s an easy bit of information to find out tyres actually have a “born-on” date, and it’s listed right on the tyre itself.
How to Find Your Tyre Load Index and Tyre Speed Rating
If you’re unable to clearly read the tyre size from the sidewall of your tyre, you can also locate your tyre load index and tyre speed rating in your owner’s manual, inside your glove compartment and gas tank hatch and on your driver’s side doorjamb. Of course a tyre professional will always be willing to help