Do replacement winter tires have to be the same size?

[dynot]

Forgive my ignorance...I'm looking for used winter tires for my 2008 328xi which currently has 225/40 R18 on the front and 255/35 R18 on the back.

When I called my dealer he told me I can only get 17s for winter tires and what he offered me was a winter kit for over $3K so I'm looking to see what's available in a used set.

I know i can go from 18s to 17s because the dealer said so but my questions are 1) do the other numbers have to be the same as what I currently have on front and back and 2) can I put the same sizes in front and back?

Thanks

[dpritchett]

You can go square - have the same size on all four wheels. The sizes do not have to march what you have on your summer setup, but you do want to be sure they will fit. If you are getting them from the dealer or from Tire Rack, that should not be a worry.

[Citizen Insane]

Give tirerack a call and ask them. They can help you. I got a set of Blizzak WS70's (205/55R16) and 16" Wheels for $900 from them just recently for my 2007 328i.