Tyre guide..

[Say..."Renno"]

Heres a handy link i use all the time. It helps if you're thinking of changing your wheels and are confused about what tyres to get........

https://www.tyresave.co.uk/tyresize.html

[Eddie70]

I have often found that i get a great deal on Renault Megane tyres or others for that matter ....from Tyres Unlimited based in Cambridgeshire. They allow you to search for your size online and offer mail order delivery at fantastic prices.

https://www.tyresunlimited.co.uk (Ask for Simon ! )

[IainMW]

Lots of links to online tyre websites here viewtopic.php?f=4&t=5942

[AlexB]

The poster meant the tyre size calculator. This link is slightly better, as it includes matching tyres to the rim size.

https://alloywheels.com/tyrecalc.asp

Yes, this topic has been discussed earlier.

[Gazwould]

The maths is a bit irrelevant as tyre manufacturer's don't keep to the sizes.

[AlexB]

Revisiting many years after...

When changing the rim/tyre size it is possible to bias the readings of the speedometer. This can be corrected by updating the configuration of the ABS computer with Clip or a free tool ECU Tweak, see my other thread about free software tools and EM327 interface.

With changing the size a usual concern is the insurance. I would imagine the insurance will not be affected if the new size belongs to the list of options for a given car model.