Reading a Tyre

To the uninitiated it looks unintelligible, but translating the code written on your tyre is really quite easy… once you know how.

The most obvious marking is the manufacturer’s name. Next to that is the confusing jumble of letters and numbers:

185/55R15 90V

185 is the width of the tyre, always in millimetres.
55 is the tyre sidewall profile, or the sidewall height expressed as a percentage of its width — 55% of 185mm.
R means it is of radial construction, as opposed to a cross-ply.
15 is the diameter of the wheel, always in inches.
90 is the load indicator, in this case 600kg per tyre; tyre dealers keep copies of the load index.
V is the speed rating: the maximum speed the tyre can take at the rated load, in this case 240km/h.

Car tyre speed ratings

S 180km/h
T 190km/h
U 200km/h
H 210km/h
V 240km/h
W(ZR) 270km/h
Y(ZR) 300km/h
ZR Above 240km/h

What is my tyre’s profile?

The tyre profile is the depth of the sidewall, or the wall at the side of the tyre. The 185/55R15 tyre example has a profile or sidewall that is 55% of the 185mm width. A low profile tyre is usually 50% or below. Though low profile tyres allow greater control of the car, and better handling around bends, they can also result in a firmer ride.