RX-7:Wheel Fitment Guide
Like tires, the more the rims cost, the better the quality. Cheap rims use very poor castings with low quality metals. This ends up with a rim that bends or cracks very easily. Also, you really don't want to go with an ultra-light weight rim on the street, as bump and pot holes can easily damage them!
The fronts can go to 8" with no modifications 9.5" wide requiring less static forms of fitment, including increasing camber, tire stretching, and fender rolling. The rears can easily fit 10" with no modifications, 11" with stretched tires will require some relatively minor fender/quarterpanel work, 12" with stretched tires and some fancy fender pulling/rolling can fit under the stock sheet metal. the stock sheet metal at the hand of an experienced metal worker, can be pulled nearly one inch. Listed below is the maximum width wheel, with its maximum and minimum fitment offsets, should you choose to go with a narrower wheel, your calculation to find an offset placing the wheel in the same position is as simple as subtracting from the minimum.
Again, tire profile has a huge bearing on if you run into fitment problems, so try and see if you can find someone who has run a similar combination of rim specs and tire models you've been eyeing. If you do run into minor fitment problems on the inside (i.e. suspension), you can use spacers to get some clearance. If you're rubbing the fenders, then you need to get your fenders rolled. Rolling your fender is the process that bends the inside lip upwards for additional clearance for your tires.
DISCLAIMER: THESE NUMBERS ARE TO BE USE SOLELY AS A GUIDE.
"Rim width" = width of the wheel from bead to bead, actual width typically adds 1" to manufacturer provided measurement, if more than 1" beyond bead to bead measurement, additional calculations required
"Minimum offset" = for those going for the flush look; pushes wheel toward the outside flush with the fender, sometimes beyond, including stretching tires to fit under the fender
"Maximum offset" = usable highest offset usable and clear all inner suspenion components; highly dependent on tire size
Minimum fitments will require some more exotic forms of fitment, including but not limited to, fender rolling/pulling, increased camber, increased roll stiffness, and tire stretching.
Front stock is 7" et 40 7" Maximum offset et 47 8" Minimum offset et 30 with stock suspension settings and no fender modifications 9.5" Minimum offset et 15
Rear stock is 7" et 40 7" Maximum offset et 65 10" Minimum offset et 28 with stock suspension settings and no fender modifications 12" Minimum offset et 2