What are the largest wheel/tire combinations that will fit a 1969 Firebird?

Question

I recently put a 455 in my '69 firebird to do some racing but can't get that horse power to the road with the standard wheel/tire combination. I would like to go with a 245 or so (bigger) up front and a 305 or so (bigger) in back but am not sure if they will fit the factory wheel well. I don't want to cut any metal.

Answer 1

Looks like 275's are the max

The March 2000 issue of Car Craft has an article that deals with maximum wheel and tire sizes for various cars. It has a section on the 67-69 Camaro and Firebird and below is the text of that portion of the article.
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'67-'69 Camaros and Firebirds

15-inch: 15X8 with 4.5-inch backspacing front and rear. With some tires the rear shocks will have to be mounted inboard; if you do that, some combinations of 9-inch wheels will work with 5.5-inch backspacing.

16-inch: 16X8 with 4.5-inch backspacing front and rear. The rear shocks will have to be relocated inboard. Use tires with an aspect ratio of 50 or less with section widths of 245 to 250.

17-inch: 17X9 with 5.5-inch backspacing front and rear. There may be lower control arm contact with some steering gears. Use tires with an aspect ratio of 40 or less and section widths of 245 to 255.

18-inch: 18X9 with 5.5-inch backspacing front and rear. Use tires with an aspect ratio of 35 or less with section widths of 245 to 25 in front and 275 in the rear.

Answer 2

tub it out in the back, and put some huge racing slicks on the back end. that will solve your problem.