Can You Change the Tyre Size on Your Car?

By David Sholicar

If you’re thinking of changing the size of your car tyres, there are a couple of things you need to think about first.

Tyre size illustration

To begin with, are the tyres currently on the car the size recommended by the manufacturer of the car? If they’ve been changed already (for example to be wider than recommended), and you go wider still, you may be beyond the safe tolerance of the car’s handling ability. So, make sure you know the original recommended tyre size.

Restrictions on tyre size change

The brake disks have got to fit the wheels, so it’s no use opting for tyres that can’t accommodate the brake disks from the original wheels. Some people use a rule of thumb which states you shouldn’t go up more than 1.5% or down more than 2% from the original tyre size. Many people recommend sticking with the same rim diameter.
The other thing to be aware of is that if your new tyres have a larger diameter than the tyres that the manufacturer recommended, your speedometer may not show a speed as high as the one you’re actually travelling at. And vice versa - tyres that have a diameter that’s smaller will make your speedo show a higher speed than you’re actually doing.
In fact, the best course is to talk to the tyre fitting experts at somewhere like a Protyre garage, where they deal with every type of car from family saloons to performance and sports models, to prestige marques and off roaders. They know what works and what doesn’t, and will be able to give you practical advice.

Reasons for wanting to change tyre sizes

Be clear about why you want to change the car’s tyre sizes. Some people feel the car functions better with wider tyres. They may point to increased braking response, and shorter braking times. Many feel that wider tyres help cars to corner more accurately and handle more responsively.
However, wider tyres are usually more expensive, both in themselves, and in the fact that they use more fuel. Tyre noise and vibration can be greater with wider tyres. And they don’t drain water as well as “normal” sized tyres - which means that in very wet conditions, you are more likely to aquaplane.
The lower likelihood of aquaplaning is the reason that some people want to change to narrower tyres. These tyres are also better in winter driving conditions. If noise when driving is a concern, the lower noise and greater comfort of narrower tyres may be deciding factors. And of course, you don’t have to pay the premium that comes with wider tyres.
The disadvantages of narrower tyres are the mirror image of the advantages of wider tyres. Narrower tyres don’t corner so well, have less grip and slightly increased braking distances.
All of these considerations need to be taken into account: so don’t let looks alone rule your decision on tyre sizes

Want a professional's opinion for peace-of-mind?

Book your vehicle in for a Free Tyre Check at Protyre. We have one of the largest network of garages across the UK with Free Tyre Checks available at every Protyre garage.

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About the author

Article Author Photo
By David Sholicar
David is the National Retail Operations Manager for Protyre. One of David’s areas of responsibility and expertise is dealing with the DVSA and MOT’s for Protyre. As the Authorised Examiner Designate Manager ( AEDM ) David deals with applications for changes to the many Vehicle Testing Stations ( VTS’s) including managing the growth of the Number of MOT testing stations that Protyre operate, allocating MOT tester roles, and monitoring the MOT Test logs to ensure that Protyre MOT standards are maintained as the best in the industry.
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