17" wheels (sport) - ... I can't recall off the top of my head
16" wheels (SE) - 185/50R16 81V
15" wheels (base) - 175/60R15
I started with the 16"s, and then went to 15s because they were more comfortable.
I use a non-standard size, 175/65R15, which is slightly bigger than normal, but there are more tyres available in it, and it is cheaper because it is on more cars. Note that if you use a non-standard size, in theory you should tell your insurance company.
Thanks for all the info