New Warnings About Tyres

Monday, 31. May 2010

Recent discussions regarding the use of winter tyres in the UK following our harsh winter has spurred on many to provide more advice suggesting that winter tyres may not be necessary if drivers simply treated tyres with a little more respect. Simple maintenance such as the regular checking of pressures would be a start. The National Tyre Distributors Association have followed up with the following points when replacing tyres:

Tyre size markings across an axle must be identical.
Tyre construction across an axle must be the same
The load index must be equal or be higher than the manufacturer approved tyre for the vehicle
It is recommended that the speed rating is either equal or greater than the original approved tyre.
Mud and snow – winter tyres should ideally be fitted in complete sets and should not be mixed with other tyre types across an axle.
It is recommended that when fitting two new tyres, they are fitted to the rear axle unless rear tyres are a different size to the fronts or the vehicle manufacturer’s handbook states otherwise.
There may be special dimensional requirements preventing the mixing of tyres such as 4WD vehicles.

I know I have provided this information before but do you know what the markings mean on a tyre? Lets take a tyre that reads 195/65 R 15 91 H. Here’s what the markings mean:

195 : The width of the tyre in mm, also called the section width.
65 : The aspect ratio is the ratio between the sidewall height (side of the tyre) and the width of the tyre. It is expressed as a percentage.
R : The type of construction (R for radial).
15 : The internal diameter of the rim in inches.
91 : A tyre’s load rating is identified by a number and corresponds to the maximum load the tyre can withstand at maximum pressure.
H : Speed rating (also known as Performance Index). Indicates the maximum speed at which the tyre can bear a load corresponding to its load rating