When it comes to buying new tyres, it is easy to make the mistake of thinking that a tyre is a tyre, and they are all the same. However, if you take one look at the baffling array of numbers and letters on your tyres, you will soon know that life isn’t that simple. Here’s what you need to know.
Decoding the numbers and letters
There may seem to be a disproportionate amount of information on your tyre, they’re just tyres, after all, but each letter and number provides an important piece of information.
A typical tyre serial may look like this: where N = a number and L = a letter: NNN/NN LNN NNL e.g. 195/55 R15 87V. The first three digits describe the width of the tyre, the middle digits and number combination describes the profile and rim, and the final three figures relate to the speed rating.
195 = width in mm – in this case, the tyre is 195 mm wide.
55 = tyre aspect ratio – this set of numbers tells us how thick the tyre wall is, as a percentage of the width. An aspect ration of 55 means that the tyre profile is 55% of its width.
R = construction – the letter after the aspect ratio denotes the way it is constructed. Most modern tyres are of radial construction (R) but some are bias (B) or diagonal (D).
16 = diameter – this describes the inner diameter of your tyre rim in inches - the wheel size it will fit.
87 = maximum tyre weight. This last set of numbers tells you the load weighting, which is the maximum weight, in kg, that each tyre could carry whilst properly inflated.
V = speed rating. At the end of each tyre definition is a letter, which tells you the maximum speed that the tyre can handle, assuming that it is properly inflated and under the maximum load. A speed rating of Q is the lowest and means that the tyres can cope with speeds up to 100 mph. From Q-U and H, the rating rises in increments of 6 mph e.g. R = 106, S = 112 etc. up to H which is 130. V will tolerate up to 149 mph, Z over 149, w 168, and Y 186.
Manufacture date
There is an additional four-digit number on your tyre wall which tells you when it was manufactured. The four digits represent the month and year of production; so 0921 means that the tyre was made in the 9th week of 2021. The first two digits can go from 01-52, with a number for each week of the year.
If you need a new tyre, it is important that your new one matches the rest so that it will fit in the first instance, and function as it should. If you are unsure of your tyre size and specifications, head to your nearest tyre specialist. They will be able to suggest the right tyres for you, fit them, and balance your wheels so that you get optimal performance. For more advice, follow Trust A Garage on Facebook or Twitter.