1st gen Firebird wheel and tire combo fitiment

[LONE*STAR]

What do you guys think of these specs, I am currently finishing the c5 conversion front and rear and my rear outer fender lips where rolled by the previous owner to fit some Et Streets.

https://static1.pt-content.com/images/pt/2010/01/Screenshot20100120at35400PM-1.png

[Tom Welch]

on my 67 bird i havent rolled the fenders and I am using 245/45r17 on 17x8 wheels in front, 275/40r17 on 17x9 on the rear, fits good, no rubbing except at full lock when turning, fronts rub the frame, a steering stop will fix it though. The 285 will probably fit with the rolled lips but I would mock up something to check it before I went forward with a purchase, I did and Im glad for doing it.

[LONE*STAR]

will an inch difference in tire height front to rear look bad???

[LONE*STAR]

I have read quite a bit on this combo working fine just wanted confirmation that it looks within range. Any other help??

[68byrd]

When we put the 17's on the byrd, we started with 17x7 with 215/40 17's on the front. The rears were 275/40 17's and were about 1" taller. Looking at the car the front side wall looked a lot smaller than the rears. This made the whole car like weird. The fronts were sold a week later and replaced with 17x8's w/ 245/45 17's. It looks much better. The front and rear tires are almost the exact same height.

[LONE*STAR]

thanks 68byrd,

The final set you put on the bird per that calculator is the same exact size @ 25.7 the first fronts were 23.8 inches that's essentially 2" difference, I have no doubt that looked bad. However I see builders and shops on here all the time recommend between a 245/40 245/45 and 255/40 all the time for 1st gens with 18" wheels.

Can any of the shops that regularly fit 1st gens with wheel and tire combos interject?

[68Formula]

If you look at the wheel wells, the back are a little bigger than the front, so IMO, a slightly taller tire would look really good. I have 17s with 25.7" tall tires now, but if I ever go 18s it will be a 245/40 and 275/40 combination.

[JayR]

I'm not a Pontiac expert but I've heard some of the Firebirds have the same 60.5" rearend as Camaros and some have wider ones. Your rear dimensions look like they might be intended for the wider one. Typically, we recommend around 5.25" BS on a 9 for a 67-68 Camaro.

Measure from your mounting pad with a straight edge to the inner and outermost obstructions around 10 and 2 o'clock in the wheelwell and let us know what you come up with. Measuring from mounting pad to mounting pad will also determine which rearend you have.

[Jeffrotech]

I've got a '68 Firebird as well. I'll take the same measurements as soon as I chance.

Say - where did you get that cool tire/wheel size calculator???

[Bigblue73]

Exactly - very useful tool when dealing with customers.

[LONE*STAR]

I've found a few of these online... I think it's flash or something cause there all the same but I find them hosted on different sites.

http://www.bigcustomwheels.com/info_specs.jsp

[LONE*STAR]

I have my rear end getting the c5 makeover so the only measurement I have is housing end to end @ 57 inches...

Anyone have a picture of 285/40/18 on a 9.5 inch wheel, I'm wondering if it looks a little to fat on that size wheel?

[DriverzInc]

From experience with these cars, specifically, run a 275/40/18 on a 9 or 9.5. The 285/40/18 will mount up on a 9" wheel, however, it is already a tight fit on these cars with a 275, and pushing the envelope any more may put you into trouble. Call, and we can explain more. I don't want to give away too much info here, but with some careful measurements, we can work magic.