Alloy wheels

Hi guys,

I'm thinking about getting a set of winter alloys. I have the five spoke 'Serengeti' 17"s at the moment. Any advice on what size i should go for would be greatly appreciated, am I right in saying the 17"s are expensive for tyres? Was thinking of painting them black to match the car and save me having to wash them!

Cheers, craw

Mine are 17s to I'm picking up some 15s next week going to
Rap them in some A/T for winter