Monday, September 21, 2009

Tyre Markings

At the Total Kenya Motorshow I had a chat with some chaps at the Yana Stand who explained to me what the numbers on a tyre mean. Heres a summary

1.Tyre width
This three-digit number refers to the overall width of the tyre in millimeters.

2.Profile/Aspect ratio
The relationship between tyre height and tyre width. The higher the number, the taller the sidewall. The lower the number the smaller the sidewall, hence the term low-profile tyre

The letter R indicates radial-ply as opposed to bias-ply tyre construction.

4.Wheel diameter
This number indicates the size of wheel the tyre is designed to fit onto.

5.Load index
A relative scale that indicates how much weight the tyre is certified to carry at maximum inflation. It can range from zero to 279. The higher the number, the greater the load-carrying capacity.

6.Primary speed rating
This specifies the maximum speed at which a tyre is certified to carry its maximum load. Primary speed ratings range from A (lowest) to Z (highest). (Some tyres also carry more specific secondary ratings.)