Tyre size
 

I need to replace tyres and it was suggested I change size - I didn't even know you could! Right now, my C30 currently has 205/50 R17 tyres on it. I note that you can put 195/65 R15 tyres on, and as these are somewhat cheaper it is something than appeals to me (given all 4 need replacing).

What are the cons/pros of different sizes?

You do realise you need to replace actual wheels aswell, yea? (just checking). Car would look a bit ridiculous on 15', also if you have 300mm discs calipers might not clear it, but in general its doable. Whether you save enough to justify it?, thats another story...
you can always go 225/45/17 on current wheels, sometimes those are bit cheaper.

Well I had assumed that was necessary but, as I say, I was told that you could just change them, that there was some tolerance....

...but I don't know and that's why I asked! :)

yes, technically those 2 sizes are almost identical as for diameter etc.

whether 15' rim clears your calipers - that I dont know. 16' Focus alloy barely clears my 320mm set. If you have 300mm on front, it may be close call aswell.

whether your car have any issues with those, apart from fitment problems - dont think so, will probably get more wobbly but BCM/DSTC shouldnt notice difference.

https://www.volvoforums.org.uk/attac...1&d=1562337153