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August 19, 2014How to Understand Your Tyre Size

Buying new tyres for your car is a complicated business. There are EU labels to consider, not to mention the different codes and ratings you need understand before you can even visit your tyre fitter! Here we help unravel some of the mystery and explain some key aspects to look out for.

How to Understand Your Tyre Size

Each tyre has a series of letters and numbers along the walls. These are codes that identify the width of the tyre in millimetres, the profile (percentage of the width), the diameter of the inner rim plus the load and speed ratings. You need to look at the side wall of the tyre and it will be written on like this:

The code you will see will look something like this – 225/50/R16/92S. The coding means:

225 = this is the width of the tyre in millimetres.
50 = this is the aspect ratio (or profile), or the ratio of the tyre’s width to the height. The height of the tyre sidewall is represented as a percentage of the width.
R = refers to Radial which is a type of tyre, but this information is not required when ordering your tyres. Almost all tyres are radial tyres but if there is no letter then it is a cross ply tyre.
16 = is the actual wheel size; the diameter of the tyres inner rim, in inches
92 = this is the load capacity and determines how much weight your tyre can carry.
S = this is the speed rating and indicates the speed your tyre can sustain at full load.

Based on the information you give them, the dealer will assess if you need tyres for high speeds or, for example, family use where convenient driving and safety are the most important properties of the tyre. They will then offer you various alternatives to choose from – the tyres most suitable for your requirements, against the budget you have to spend.

Tyre Speed Rating Chart

The table below shows you what each letter represents:

Code mph
A-J 62
K 68
L 75
M 81
N 87
P 94
Q 100
R 106
S 112
T 118
U 124
H 130
V 149
Z Over 149
W 168
(W) Over 168
Y 186
(Y) Over 186

If you are still confused make sure you get in touch with the experts here at Treadfirst and we’ll happily help you find the perfect tyres to meet your requirements and your budget. Visit our website to find your local dealer and phone them directly!

Get in touch today for the best quality advice, competitive pricing and a personal service

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