Every tyre sidewall carries a series of numbers and letters that provide precise information about its dimensions, load capacity, speed rating, and age. Understanding this code helps you buy the right replacement tyre and check whether a used tyre is suitable for your vehicle.
Reading the Size Code
A typical tyre marking might read: 205/55 R16 91V. Breaking this down: 205 is the tyre width in millimetres; 55 is the aspect ratio — the height of the sidewall as a percentage of the width; R indicates radial construction; 16 is the wheel diameter in inches; 91 is the load index; and V is the speed rating. These four figures together define the tyre's size and performance classification.
Load Index and Speed Rating
The load index is a numerical code indicating the maximum weight each tyre can carry. An index of 91 corresponds to 615kg per tyre. Never fit a tyre with a lower load index than the vehicle manufacturer specifies. The speed rating letter indicates the maximum sustained speed — V means up to 149mph, while H covers up to 130mph. Fitting a tyre with a lower speed rating than required is not recommended on UK roads.
Finding the Manufacture Date
On the sidewall you'll find a four-digit DOT code, for example 2422. The first two digits represent the week of manufacture and the last two the year — so 2422 means the 24th week of 2022. Tyres over five years old should be inspected carefully; those over seven years old should be replaced regardless of tread depth.
Need Help Choosing the Right Tyre?
If you're unsure which tyre your vehicle needs, call 01484 627456. Our mobile tyre fitters in Huddersfield will identify the correct specification and bring the right tyre to your door.
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