After taking a test drive in a TDi Scout I spent a while having a good look around the car. I noted for instance that the underbonnet area had a good sound insulation layer and that it had what I thought was a full size spare. However on inspection I noted that the spare was a 16" wheel as opposed to the standard 17". When I asked the dealer about this he said that the space for the spare wheel could not accommodate a 17" wheel but not to worry the 16" spare still had the same rolling circumference as the 17". He couldn't explain how it worked!

16" diameter wheel = 50.3" circumference and 17" = 53.4" circumference. Anyone out there explain this - or is the dealer mistaken? I hope not because the wheels really should be going round together!

(BTW the car was excellent - most impressive were the rock solid feel and impressive build quality).

The outside of the rubber tires will be the same diameter, the diameter of the metal wheels is different.

The profile of the tires is different . The 16" will be a 60 or something while the 17" will be a 40 (numbers entirely made up BTW)

Don't worry; the 16" spare will have a suitable size tyre to be the same rolling radius as the 17" as otherwise fitted.

My vRS has 225/40 18 wheel/tyre combo but my spare is a 205/55 16.

If you get the actual tyre sizes, you can do a comparison at Car Bibles : The Wheel and Tyre Bible Page 2 of 2 where there is a little calculator tool.

As an example.....

Just to add - I am the only one that finds the fact that a dealer salesman couldn't explain this somewhat scary?

.... or you can use our own, Briskoda tyre calculator, here;- BRISKODA - The Skoda Forum and Community - Tyre Calculator

.... or you can use our own, Briskoda tyre calculator, here;- BRISKODA - The Skoda Forum and Community - Tyre Calculator

I think thats only available to Freedom members. Perhaps I should have tried to persuade him to join up instead of linking to outside sites!

Afaik the 55 bit in say 205/55 is the ratio of the sidewall to the width, ie 55% of 205mm Work that out, x2 (if you are working out the diameter rather than the radius of the wheel) and add it to the wheel size….say 16’’ and you have the diameter of your wheel. Then do your thing with pi’s n stuff and hey presto, a perfect pi thingy……………..I must stop watching all these cookery programs.

Just to add - I am the only one that finds the fact that a dealer salesman couldn't explain this somewhat scary?

No your not but then it doesn't suprise me as some seem to know little technical detail about what they sell (I guess they don;t have to and are not interested - if they were they wouldn't be salesmen!)

Sorry to resurrect this thread but have been on holiday.

Many thanks for useful replies but especially to andy2407 for his info on the Wheel and Tyre Bible site.

I didn't realise how much there is to wheel/tyre combinations!