Tyre Hieroglyphics - What Car Tyres Sidewall Markings Mean

Have you ever noticed that tyres have moulded markings on their sidewalls? You’ll probably have spotted the maker’s name but does the rest mean anything to you? Can you tell what 205/70R14 88 T is all about? Perhaps not yet but understanding these codes could save your life. Why? If they show your tyres aren’t the right ones for your car you can arrange replacements.

We can start by breaking down the example above; the markings denote the tyre size, construction, and load and speed rating. How? Like this…

205 – This is the width of the tyre’s section in millimetres. The section 205 is a little over eight inches wide.

70 – This is the tyre’s aspect ratio, the sidewall’s height expressed as a percentage of its width. Here, the height is 70 per cent of the width. ‘Low profile’ tyres are fashionable so aspect ratio figures go as low as 30. Ultra-low tyres like this give tremendous grip but you pay for it, in a poorer ride quality and very little protection for your wheels against kerbs, potholes and speed bumps.

R – The next letter indicates the tyre’s construction. Here, R means radial.

14 – This next number is also simple. The figure 14 refers to the diameter of wheel the tyre will fit, in inches.

88 – Not so simple but extremely important. This tyre load index is a code for the maximum load capacity of the tyre when driven at its maximum rated speed. The figure 88 denotes a rating of 560 kilograms. Car tyres need to be correctly rated for load.

T - The last letter indicates the tyre’s speed rating. The letter T means the tyre can cope with extended use at a maximum speed of 118 miles per hour. The top speed rating is Z, which appear on tyres for cars capable of maintaining 149mph and above.

There are other tyre sidewall markings but most are for the attention of the tyre fitter. Markings show the tyre complies with EEC, ECE and US regulations. There might be an arrow symbol showing the tyres’ direction of rotation and there’ll be a ‘TWI’ mark indicating where the running surface’s tread wear indicator lies. There will also be a safety warning, perhaps the country of manufacture, whether the tyre is tubed or tubeless, and coloured markers showing the fitter where to fit the tyre in relation to the wheel’s valve.

All these are largely for the fitter’s information but there’s one marking you’re advised to note. The last four digits in the ‘DOT’ code reveal the tyres’ date of manufacture. Four-digit codes began after 2003 so if you see, for example, the code 3 0 0 8, the tyre was made in the 30^th week of 2008. You should never use tyres over 6 years old but a good tyre fitter won’t fit ‘new’ tyres that are beyond their sell-by date.

It’s true that checking your tyre markings could save your life, simply because underrated tyres could fail, especially under high speed/load conditions. The right tyres could save you something else –under-specified car tyres can invalidate your insurance.

For more advice about which car tyre is best for your car then ask our experts at Merityre.co.uk.