Wheel SizingWheel sizing can vary based on rim diameter and model of car, however there are some general guidelines to help you choose wheels.
Overall, the outer tie rod end limits backspacing on 14-16' rims to 3.25" with Wilwood brakes.
17" and larger diameter wheels will clear the tie rod end and allow much wider wheels to be used.
B,E and F-bodiesThe B,E, and F-body cars with their generous fenders are far less sensitive and will allow more outside width without issue.
In 14-16" sizes, a 7" rim with 3.25" backspacing is very common, while 17" and bigger wheels will easily allow 8" or 9" widths with 4.5" or 5.5" backspacing.Obviously, using 17" rims opens the door for many tire widths that otherwise would not fit. There's another benefit not seldom mentioned - scrub radius. With the larger offset rims, scrub radius is reduced substantially, drastically reducing feedback to the driver, steering effort, and steering forces at the spindle, making for a smoother, more comfortable, and more predictable feel. This is a major design parameter with most new cars, and one of the primary reasons, along with increased stability, that new cars have wider suspensions and wheels with lots of backspacing.
Although 18" and bigger rims begin to have that modern car look, 17" rims will still maintain the old "musclecar look" provided care is taken with tires. There are so many tires on the market now for 17" rims, almost any look and style desired is possible. Using 17X8 rims at all four corners, you can achieve an easy "pro-touring look" by using 245/45/17 tires. If the classic Musclecar look is desired, you can run 225/50/17's on the front, and 275/50/17's on the rear - in the tech pages, check out the gearing and tire size calculators to help you convert tire numbers to overall width and diameter.
http://www.reillymotorsports.com/alterktiontech.shtml 
