need backspacing suggestions for2nd gen Firebird

[SD428]

Got a 1970 Firebird that is getting painted and I'm saving for wheels. I have the stock 14x7 wheels with 245/60/14 BFGs. I personnally like relatively short tires on the early 2nd gen fbods. I think I'm going to go with 285/40/17 (17x9.5) and 255/45/17 (17x8) - I'm just not sure of the what backspacing would look the best. Generally I don't like the wheels to stick out a lot. Anybody have a similar setup that they really like or would change slightly if they could choose all over again?

[jerhofer]

I have a 1977 Camaro with 255-45's on 17x8 wheels front and 285-40's on 17x11 wheels rear. The backspacing is 4 3/4" front and 5 3/4" on the rear. They fit perfectly. I would think the fit would be pretty comparable to your Firebird.







www.jerryforthofer.wordpress.com

[SD428]

Thanks Jerry. Nice car.

Is there anybody here who has tried both a 5.5 and 6 inch backspacing on 9.5 wide rims on the back? I'm wondering whick would look/fit better. Maybe I should go with a 5.75 bs

[NOT A TA]

I have 17" 9.5's with 5.5 backspacing with 275 40's on the FRONT of my 70. I'm going to have the car apart soon and can swap one to the rear and take a pic for ya when I do it. Rears are currently 315 35's on 11" with 6.75 BS. I've been very happy with them. MEASURE YOUR OWN CAR! Do NOT use other peoples measurements without checking your car and considering suspension, payloads, and use.

I'm going to 18" Rushforths and a 285/295 combination. Moving up to 18's to clear the 14" Baer brakes. Hard to believe the new rotors will be as big as the original wheels were!

[SD428]

Thanks Not a TA -

That would be great if you get a chance to take a picture.

You nailed the look on your current setup - especially cool with the gumball. Looking forward to seeing your new combination.
If I ever get my car back from paint detention, I'm going to start measuring. Those 315s got me thinking again.

[NOT A TA]

Thanks! Here's a better look at the 315 on 11" since you're considering them, and a pic so you can see where they line up with the fender since you have an idea of how far out you want yours to stick.. Not sure what you're after but you can't "tuck" a 315 in a stock wheelwell if you're planning on dropping it in the weeds.

[jp455]

Is nobody running 19s on second gens? Just curious.

[1973Firebird01]

Not a TA, what brand of tires are those? Do you have any rubbing issues with your 17x9.5s up front?? Are you going to go to an 18x9.5 up front with the Rushforths??

[JayR]

Here's one we put 19s on. It's all DSE so his widths and backspacing won't help but will give you an idea of the proportions which I think are spot-on for a 2nd Gen. 8s and 10s will look and fit great.

[NOT A TA]

Not a TA, what brand of tires are those? Do you have any rubbing issues with your 17x9.5s up front?? Are you going to go to an 18x9.5 up front with the Rushforths??

Tires on the car were Yokohama AO-32's the new ones are the upgraded version called AO-48. They are a DOT R tire designed for track days. They will not get hot enough at an auto X to work their best so keep that in mind if you're not going to be going to road course track days.

The 275's on 9.5 17's just touch the fat Hotchkis swaybar at full lock. I will be putting a radius limiter in when I install the wider tires. Rushforths will be 18 X 10 all around but different backspacing F/R. Keep in mind I have more suspension travel than a lot of folks going for "the PT look" with the car really dropped tucking the tires. If you try to drop the car till you tuck the tires you'll have rubbing issues. My car looks lower than it really is due to the optical illusion created by the sidepipes causing it to appear lower. It's almost 4" lower than it was stock but not as low as a lot of people like to see now. Note the gap between the tire and fender lip at rest. The car does drop an inch or two at speed on track because of the TA spoilers, flares etc. You can see the difference in ride height in high speed track pics.

[aronhk_md]

John....been wondering how you are setting the backspacing on the new wheels. If they are all 18x10's and you did more backspacing on the rear then the lip on the rears will appear smaller to an observer. If only a small amount it might not be noticeable. Maybe its not even a concern to you?

I kind of thought you had the perfect wheel lip alignment with the old setup for your ride height, but if you are going to smaller wheels/tires in the rear if you used the same backspacing as at present obviously your wheels would disappear into the wheel wells.......so I'm guessing you are going to less backspacing......if I had to guess I'd say maybe 6"?

If you then kept the same BS for the front wheels, then the rear wheels will have a 1/2" smaller lip on the outside.....and that might be noticeable.

I'm just guessing here of course.....lol

I'm getting ready to make the plunge and buy some wheels too, but since the ones I'm looking at are on the cheap end of the spectrum I'm faced with the same dilemna If I go with 18x9's all around as seems likely, and went with somewhere between 5.25 and 5.75 BS for the fronts............then I should probably get the exact same for the rears. If I dont and I did for example 5.25's for the front, and 5.75 for the rear then the rears will have a smaller lip. I keep telling myself I shouldnt care....lol. Of course if I do that I might have to use them as doorstops later when I upgrade to nicer wheels cause it wont be easy to sell them........unless I find 2 buyers who each want a pair for rear wheels and plan to grab smaller fronts for themselves.

The wheels I'm looking at are either 5.25 BS or 5.75. I guess as I said, I could just do all 4 the same in either BS and get away with it for now.

[formula]

More 19s here. I think they look good but am considering some 18s for track use as the cost and selection of 19" tires is limited compared to 18s.

[plckidd]

I have 17" 9.5's with 5.5 backspacing with 275 40's on the FRONT of my 70. I'm going to have the car apart soon and can swap one to the rear and take a pic for ya when I do it. Rears are currently 315 35's on 11" with 6.75 BS. I've been very happy with them. MEASURE YOUR OWN CAR! Do NOT use other peoples measurements without checking your car and considering suspension, payloads, and use.

I'm going to 18" Rushforths and a 285/295 combination. Moving up to 18's to clear the 14" Baer brakes. Hard to believe the new rotors will be as big as the original wheels were!

Hi. This may be 10 years too late! Was wondering what the suspension setup is on your Firebird. How much has your car been lowered?