Tyres really are one of the most important components of your vehicle – after all, they’re the only parts of the car that actually make contact with the road. So it’s vital to make sure that any car you’re driving is wearing the correct size and type of tyre.
You might be replacing the tyres on your own car, or you could be on the buying journey for a new model – in between asking yourself ‘how much is my car worth?’ and ‘what sort of mpg will it do?’ you should definitely find time to consider ‘is this car wearing appropriate tyres?’
What do I need to know about tyre sizes?
If you’re the first owner of your car, the chances are, you don’t need to worry about the specification of your tyres. The car will have come wearing the recommended rubber from the factory, and you can simply find the specifications (along with the recommended pressures) on a compliance plate usually in one of the door jambs or inside the fuel filler.
However, if you want to buy replacement tyres online, are buying a second-hand car and want to make sure it’s wearing the correct tyres, or want to buy a set of winter tyres for different-sized wheels to put on during the colder months, then understanding tyre sizing will ensure you stay safe and legal.
Tyre sizing explained
Tyre sizes are communicated by code written on the side of the tyre. A typical code will look something like this:
195/55 R16 87V
195 refers to the width of the tyre in mm. Wider tyres typically offer more grip
55 refers to the profile – that’s the height of the sidewall expressed as a percentage of the width. Low-profile tyres distort less under sideways force, which means they’re often found on performance cars intended for quick cornering. But less sidewall also means less cushioning between the rim and the road.
R means it’s a radial tyre. Older cars used to use a different reinforcement construction known as ‘crossply’ tyres – these have been replaced by radials in all but historic or specialist applications.
16 is the diameter of the road wheel in inches
87 is the tyre’s load rating – how much weight each tyre can carry.
V is the speed rating – how fast the car is capable of driving safely
Why it’s important to get the right tyres
The simplest reason is that if you buy a tyre in the wrong size, it won’t fit your wheels – that’s with the exception of some show cars that use ‘stretched’ tyres.
What could be more tempting is to opt for a tyre with a lower speed or load rating than the tyre you’re replacing, saving you some cash.
However, it’s vital you stick to the recommended ratings. Not only could it be potentially unsafe if you travel faster or more heavily laden than your tyres recommend, but you could be in breach of the law and suffer an MOT failure when next tested. Your insurance may also be invalidated.
In terms of longevity, heat resistance, and wear, you must stick to the recommended tyre ratings in order to stay safe.