The tyre width is measured from end to end of the tyre including the sidewall but excluding and raised lettering or rim protectors. In this visual 255 indicates that the tyre's width is 255 millimetres.
Safety Tip: Tyre width is important as it can affect both your car's performance and how economical it is with fuel.
35% is described as the aspect ration, this mark represents the height od the tyres sidewall as a percentage of the nominal section width.
Safety Tip: Check tyre pressures regularly. Tyres with a low profile can sometimes look normal even with dangerously low pressure.
The letter R stands for Radial, the type of tyre fitting to your car. The number is the diameter of the tyre's inner rim, or the size of your wheel rim. This is measured in inches e.g. R19.
Safety Tip: It's vital to fit the correct size wheel to tyre combination in order to obtain optimum performance from the tyre.
Using the "tyre load index table" which can be found below, you're tyre's load index indicates the maximum weight in kg that your tyre can safely support.
Safety Tip: Avoid exceeding this weight as it can result in steering instability and even rupture.
Speed index is a letter which relates to the "tyre speed index table" below. The last letter indicates the maximum speed for the tyre at full load (in this case Y = 300 kph).
Safety Tip: It's really important to check your speed index as choosing a tyre with a rating too low for your vehicle can invalidate your insurance.
The manufacturing week and year allow you to understand when the tyre was manufactured and is indicated by 5118 (51 being the week of manufacture and 18 being the year of manufacture).
Safety Tip: Make sure your getting rubber that is not aged and has been exposed to the elements as this reduces the tyres life.
Tyre load index table
|Load Index||Pounds||Kilograms||Load Index||Pounds||Kilograms||Load Index||Pounds||Kilograms|
Tyre speed index table
|Speed Code||Speed (mph)||Speed (k/ph)||Category|
|L||75 mph||120 km/h||Off-Road & Light Truck Tires|
|M||81 mph||130 km/h||Temporary Spare Tires|
|P||93 mph||150 km/h|
|Q||99 mph||160 km/h||Studless & Studdable Winter Tires|
|R||106 mph||170 km/h||H.D. Light Truck Tires|
|S||112 mph||180 km/h||Family Sedans & Vans|
|T||118 mph||190 km/h||Family Sedans & Vans|
|U||124 mph||200 km/h|
|H||130 mph||210 km/h||Sport Sedans & Coupes|
|V||149 mph||240 km/h||Sport Sedans, Coupes & Sports Cars|
|W||168 mph||270 km/h||Exotic Sports Cars|
|Y||186 mph||300 km/h||Exotic Sports Cars|
|ZR||149 mph||240 km/h||Exotic Sports Cars|