[Don Plumley]

Another consideration: Bigger wheels -- primarily diameter but also width -- are generally heavier. That translates to more rolling mass and more weight on the suspension. Wider tires are of course, also heaver. That's one of the big benefits of forged wheels, in addition to their strength they are lighter than cast.

Another consideration of different wheels is tire size availability. For stock 993 17" wheels, my favorite tires (RA-1's) are not made in an optimuum front wheel size. In 18" wheels they have more options. When you are in Jack's league and run super wide tires, you have even more fun trying to source the right rubber.

Here's the math:

wide sticky + effective diameter + tire availability + wheel weight = complicated equation