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#1
03-16-2003, 05:27 PM
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ok i have been trying to find the right backspacing for my 70 firebird. i wanna do some 17's i have tried some on from other cars. he are some that i have seen
17x9.5 with 6.5 spacing 17x11 with 6.5 spacing 17x9.5 with 5.7 spacing 17x11 with 5.7 spacing 17x9.5 with 4 spacing 17x11 with 5 spacing here r some combos people hae on 2nd generation firebird and camaros. i was thinking of going with the 6.5 all around. any help thanks There are only so many green M&M's a man can eat before he wants a blue M&M !!!!(by 72lemans) |
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#2
03-16-2003, 05:27 PM
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ok i have been trying to find the right backspacing for my 70 firebird. i wanna do some 17's i have tried some on from other cars. he are some that i have seen
17x9.5 with 6.5 spacing 17x11 with 6.5 spacing 17x9.5 with 5.7 spacing 17x11 with 5.7 spacing 17x9.5 with 4 spacing 17x11 with 5 spacing here r some combos people hae on 2nd generation firebird and camaros. i was thinking of going with the 6.5 all around. any help thanks There are only so many green M&M's a man can eat before he wants a blue M&M !!!!(by 72lemans) |
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#3
03-16-2003, 09:14 PM
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I honestly don't understand how you could get more than 5", *maybe* 5.5" backspacing in the rear without making some serious modifications. Any more than that and the tires and rims will hit the leafsprings and the wheelhousing. For sure, even with 5" you will have to flatten the seatbelt mounting bulge at the front of the rear wheelwell.
In front, if you run more than 5" backspacing it's likely you'll contact the swaybar or other suspension parts at full lock on the steering. This may or may not be a problem for you. After all, the swaybar is round and smooth and a little rubbing on it when cornering at slow speeds in parking lots isn't going to hurt anything other than the paint on the swaybar. The good news is that 9.5" rims with 285/40-17s will fit on all 4 corners with 5" backspacing. You can probably get the 11s out back with 5.5" backspacing and minor modifications. I really don't see how 6.5" spacing could work on either front or rear without other mods, especially in the rear. You'd have to move the springs inboard and possibly mini-tub the thing.  ---------------------------- '72 Formula 400 12.77 @ 108 / 234/244 cam / Q-jet / 3840# / 3.23s / street tires (not DRs) '73 Firebird 400/4-speed
__________________
---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
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#4
03-17-2003, 05:55 AM
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Here's a link from a 2nd Gen site I post on for a guy that put 315/35/17's on the rear and 245/45/17's on the front...
I run 16x8's with 5" BS on my wife's Camaro.  My '64 GTO Convertible Webpage The '49 Caddy Limo Page The '72 Camaro Page |
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#5
03-17-2003, 09:29 AM
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i'm thinking about on the 6.5 too, it was on a stock camaro though. i will look into it a bit more, thanks for the help
There are only so many green M&M's a man can eat before he wants a blue M&M !!!!(by 72lemans) |
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#6
03-17-2003, 03:25 PM
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could you go any wider then 315's in the back, still on the 17x11?
There are only so many green M&M's a man can eat before he wants a blue M&M !!!!(by 72lemans) |
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#7
03-17-2003, 03:26 PM
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 There are only so many green M&M's a man can eat before he wants a blue M&M !!!!(by 72lemans) |
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#8
03-18-2003, 05:12 PM
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These are three combos I have seen. The first is a guy that worked at Flowmaster with a early 70'sFormula:
FRONT: 17X8 ZERO OFFSET 4" BACKSPACE 255-45 REAR: 17X9.5 1 1/2" OFFSET 5" BACKSPACE 275-40 This one was on Hot Rod TV 70 Z28: Yokohama AGS Front- 275-40 17” Tire 9.5” Rim @ 6.5” Backspace Rear- 315-35 17” Tire 11” Rim @ 6.5" Backspace Tires are 25.7” Tall I found this one on the web: 17 x 9.5" for the fronts, and the 17 x 11" for the rears. On both, I chose the 5.7" of backspacing that Jeff recommended. I went with the 275/40/17 tires on the front, and the 315/35/17 on the rear (Yokohama AVS Sports all around). Can anybody validate any of these size combos? |
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#9
03-18-2003, 07:55 PM
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73ta has a point i have seen these on t.v and so on and they work.
 1970 t/a clone g-machne in the works |
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#10
03-18-2003, 11:17 PM
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would 335's work on the 17x11 without rubbing?
1970 t/a clone g-machne in the works |
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#11
03-20-2003, 03:03 PM
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It would be nice if someone with any of these sizes could tell us about any problems. The hot Rod TV Z28 was just sitting still and they didn't talk about a road test. They did use a device that mounted to the axel and had a tire on it that they could adjust the rim width and backspacing on the fly. Forgot the manufacturer of it but it worked pretty slick. I'm about ready to buy new wheels and tires, but want to be sure of any clearance issues with the larger sizes I previously stated. The sizes on the car from the guy at Flowmaster had not rubbing clearance issues in real world driving. I'm wondering about the other two!
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#12
03-20-2003, 03:03 PM
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It would be nice if someone with any of these sizes could tell us about any problems. The hot Rod TV Z28 was just sitting still and they didn't talk about a road test. They did use a device that mounted to the axel and had a tire on it that they could adjust the rim width and backspacing on the fly. Forgot the manufacturer of it but it worked pretty slick. I'm about ready to buy new wheels and tires, but want to be sure of any clearance issues with the larger sizes I previously stated. The sizes on the car from the guy at Flowmaster had no rubbing clearance issues in real world driving. I'm wondering about the other two!
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#13
03-20-2003, 03:54 PM
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I know what you mean. it was horsepower t.v. with chuck and joe. it was chucks Z28 camaro that they put the 17's on.they did use some type of device to figure out the backspacing. you buy the tires u want, then u mount this device to the tire and you can adjust to figure out the backspacing.I dont think there would be a problem or else they woulda said something. they did do a brake job on it and still used the same wheels.So i'm thnking the setup worked out ok.I as thinking of buying that device they used.I seen it in jegs a while back
1970 t/a clone g-machne in the works |
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#14
03-20-2003, 09:00 PM
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There are a couple of wheel simulators available on the internet. I bought one when I was figuring out all the dimensions for the billet wheels I had made. Makes everything fairly easy, andnow that I have the wheels/tires on the car, everything fits the way it should. I did widen the wheeltubs on the back, but the fronts are stock and I was able to fit 275/35X18,s on a 9.5" wide rim and 5.375" BS.
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#15
03-24-2003, 10:10 AM
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 is this your gto,with the mini tubs?1970 t/a clone g-machne in the works |
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#16
03-24-2003, 10:11 AM
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do u have any pics of the 18's?
1970 t/a clone g-machne in the works |
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#17
03-28-2003, 03:27 AM
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Hmmm. Not saying it *can't* be done, but I just don't see how you can get 6.5" backspacing to work in the rear of a 2nd gen 'bird. Maybe I measured something wrong...?
In any case, I'll know for sure sometime in the next month as I'll be going through the suspension on my '73 and installing the 17x9 wheels. One thing to watch out for is just about every 2nd gen I've seen has the rear axle offset to one side or the other by as much as 1/2". I've heard this was done on purpose to keep the U-joints from lining up when the suspension is loaded, but that's just speculation. In any case, I'll be checking the rearend I'm putting in the car very carefully and will have the spring perches relocated if they're off by more than 1/4". ---------------------------- '72 Formula 400 12.77 @ 108 / 234/244 cam / Q-jet / 3840# / 3.23s / street tires (not DRs) '73 Firebird 400/4-speed
__________________
---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
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#18
03-28-2003, 11:07 AM
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ya mine was the rear passanger tire, it stuck out a bit with bigger rims. I also was gonna do the new ws6 rims on my 70 t/a. I changed my mind and wanted wider tires and the ws6 cant fit them without mods to the rims. cant wait to see pics. good luck
 1970 t/a clone g-machne in the works |
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#19
03-28-2003, 12:09 PM
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Will, are u doing chrome ws6 rims?
1970 t/a clone g-machne in the works |
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#20
03-28-2003, 04:16 PM
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fast1970transam,
Do you know someone who can widen factory aluminum rims??? I have a spare pair of these and would love to get 10.5" or 11" width out back. The rims are the polished variety, not chrome. The polishing is not a mirror finish, so it gives them a softer finish that I like better than chrome. Tell you what, if I had the money Id've gone with Fikse FM5's, 9.5" in front and 11" in rear. Sigh. ---------------------------- '72 Formula 400 12.77 @ 108 / 234/244 cam / Q-jet / 3840# / 3.23s / street tires (not DRs) '73 Firebird 400/4-speed
__________________
---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
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