Tyre speed rating explained

**Brake buster** · 14th August 2005, 12:57

Click here for speed ratings and codes

use this site to explain the speed rating of your tyre , or tyres you may want to buy,

the code is also sometimes in the tyre description,

eg, 225/45/ZR17.............Z = speed rating and the R = radius of wheel

or sometimes its 225/45/R17 and the Z will be else where on the tyre

the 225 in this case is the actual width of the tyre from inner sidewall to outer sidewall,

the 45 is a percentage of the width ( 225 ) making up the depth of the tyre from the rim on the wheel to the outer diamiter of the tyre

so a 225/45/ZR17 is 225mm wide, with 101.25mm depth on a 17 inch wheel with a speed rating of over 150 mph ( 180 mph )

just in case anyone is interested

BB

**big phil** · 14th August 2005, 15:36

Mmmm think they've changed the rating letters now ...

< 160 mph --- is a W rating
<

**scooby8272** · 23rd January 2009, 10:31

Nice

**solorider** · 23rd January 2009, 11:52

another thing to point out is just because your car has a higher speed rating than listed dont be tempted to use a lower speed rating as there are other factors also included like the acceleration,weight etc.