I have a 1981 Z28 Camaro looking to find out what is the largest rim and tire that I can put on without rubbing front or rear wheel wells thanks for any help

 

You can usaully run an 8" inch wide rim on a second gen car it depends on the " look" you want .

 

On the REAR end: personally ilike a BFG P275-60R15 on a 15x10 wheel with 5.5" backspacing and a 1/4" spacer or if you find a wheel with 5.25" Back Spacing. if this works and there may be room for a p295-50R15. Although there is a mod but its not really a mod at all. and you need to do it anyway for this size. Its you take a small 1" thick board with a rubber mallot to massage the seat belt humps in , they are soft a push right in without any adverse affects. you could do a 15X9 with 5" backspacing and a p275-60R15 BFG radial, although iam waiting to try that one still.
On the FRONT end: personally iprefer the 235-60R15 with the aforementioned combo, although ihave had P245-60R15 all around on 15x8's with 4.5" backspacing and wheel spacers on the back ones so icould rotate if iwanted to , dont forget the wheel spacers for the rear to correct the track width on 1972 up 2nd gens with same size wheels tires or 11" drums on back might not need the spacers although iwould still use some spacers for the back anyway..