Originally posted by crash
i think up until 18" it doesnt really matter. i mean if you have a 15" wheel and tire, and a 17" wheel and tire, and both wheel tire wheighs the exact sameit wouldn't make an difference, because the rim is taller, but the tire is shorter, making them still the same size together.
sorry for all the commas and if this doesnt make sense.
Not quite so.
A larger wheel has a wider distribution of rotating mass, requiring more torque to turn overall, even if the wheel weights the same as its smaller counterpart. The issue about keeping the wheel/tire diameter the same is tricky, since a 195/55/15 tire is actually slightly taller than a 215/40/17 (common size) tire if I'm not mistaken.
I think MrFatBooty answered the latter part of the original poster's question; I'm just commenting on the wheel sizes he listed...
Shingo