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jcp2vette
Tribal Scout

USA
1 Posts

Posted - 26 Sep 2013 :  11:26:21 AM  Show Profile  Reply with Quote
Hello, I want to put the largest tires on the rear of my 1969 GTO without any tubing or cutting. Does anyone assist me?

James Pindell

cortcomp
Coyote

USA
5335 Posts

Posted - 26 Sep 2013 :  11:37:35 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
On what size wheels? I have 17x9s on my 71 and would go 17x10 if they had made them in the rally 2 wheel i bought.
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Steve C.
Crazy Horse

1673 Posts

Posted - 26 Sep 2013 :  12:06:34 PM  Show Profile  Reply with Quote

1968-1972 GM A-bodies

15-inch: 15x8 with 4-1/2-inch back-spacing front and rear. Use 255/60 tires.

16-inch: 16x8 with 4-1/2-inch back-spacing front and rear. Use 255/50 tires.

17-inch: 17x91/2-inch with 5-1/2-inch backspacing front, 17x11 with 5-1/2-inch backspacing rear. Use 275/40 front tires and 315/35 rear. This is tight in the rear.

18-inch: Same as 17-inch.


Fitting Tires and Wheels
Biggest Meats For Your Musclecar

Read more: http://www.carcraft.com/techarticles/fitting_tires_wheels/#ixzz2g11OzEQp
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cortcomp
Coyote

USA
5335 Posts

Posted - 26 Sep 2013 :  3:12:51 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Excellent info to have right there!
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GtoGuy32
Cochise

USA
842 Posts

Posted - 26 Sep 2013 :  3:48:21 PM  Show Profile  Reply with Quote
I have 15" with a 5" backspace. I have a 275 60 15 on the back of my 69 Gto. No rubbing and good clearance on both sides of the tire.
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Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 26 Sep 2013 :  4:31:55 PM  Show Profile  Reply with Quote
On what width? Post a pic
Im looking to upgrade my 14's, rally 2's


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 26 Sep 2013 4:38:40 PM
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GtoGuy32
Cochise

USA
842 Posts

Posted - 26 Sep 2013 :  6:00:56 PM  Show Profile  Reply with Quote
Sorry....they are on an 8 inch wide rim. I am running BFG radial TAs and MT ET Streets in the same sizes with no issues. Will post pic later

Edited by - GtoGuy32 on 26 Sep 2013 6:01:30 PM
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Chicagogoat
Cochise

USA
823 Posts

Posted - 26 Sep 2013 :  10:15:32 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
Yes Steve C is dead on 4 1/2" backspacing is what my stock Rally II's were. I decided to try and fit the largest rear wheel/tire combo about 10 years ago. These torquey 455's don't stand a chance at hooking on the street or track for that matter. I noticed that I could fit a 15" X 10" rim back there with more backspacing. I noticed that there is 3/4" more spacing between the stock 15 X 8 rim my inner wheel well with just enough space to fit your finger. So I decided to pull the trigger on the ever popular Torque Thrust II's the stock spacing 15 X 8's in front & 5 1/4" custom backspaced 15 X 10's in back. I ended up goin with MT indy profiles in the back 28" tall & a little over 12" wide sidewalls.

It seemed like it all worked out great if you never want any passengers or drive on perfectly flat roads, yup the side fender lip would grind into the sidewall when going over speed bumps or with passengers, and the inner wheel well would rub with spirited driving around corners. I ended up cutting off 1/4"-3/8" of the lip with a whiz wheel which helped out a bunch but did not get rid of the rubbing 100%. Ultimately it came down to replacing the worn stock rubber bushed control arms for Global West units with poly bushings. This virtually eliminated body roll and keep the rear end slop to a minimum.

So if you want to run wider than stock tires in your ride be prepared to make it work or you'll be stuck with custom backspaced rims that are of course un-returnable. I've been running 325/50R15 drag radials from M&H for 5 years (almost ready for another set). These tires hook so well that it was totally worth the effort. Those MT's were 4-plys and lasted just a few years. These drag radials nowadays are the ticket, I'll never go back to an old school softer tire.

Pure Pontiac: learn it, live it, love it!

Edited by - Chicagogoat on 26 Sep 2013 11:02:24 PM
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Chicagogoat
Cochise

USA
823 Posts

Posted - 26 Sep 2013 :  11:31:47 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
I don't think there's many guys on this site familiar with M&H, but after trying the usual favorites I love 'em and am sold for life on these. They're very aggressive yet all around performers. All business no white lettering http://www.mandhtires.com/M-H-Drag-Tires/M-H-Drag-Radials/325-50R15#.UkT5sxDW6RM


Pure Pontiac: learn it, live it, love it!
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cortcomp
Coyote

USA
5335 Posts

Posted - 27 Sep 2013 :  12:24:18 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Man they look business. I am running Nitto 555 street tires on my 17x9s and they hook nice on the street (like CRAZY on the street). They make a drag radial too in the 555 series, never tried it.
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Chicagogoat
Cochise

USA
823 Posts

Posted - 27 Sep 2013 :  12:49:54 AM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
I would think that a bigger rim like 17's may allow you to go with deeper backspacing since the 15's will hit the shock mounting bracket and still be shy of the inner wheel well. (at least on mine it does) Plus a bigger rims have tires with less sidewall which will not buldge out like the fat sidewalls on my 15's.

But 17's are the biggest wheels that are practical on these cars, I noticed that there's a lot of profiles available at that size to my surprise. Anything bigger than 17's are not my cup of tea anyway.

Pure Pontiac: learn it, live it, love it!
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GtoGuy32
Cochise

USA
842 Posts

Posted - 27 Sep 2013 :  12:59:27 AM  Show Profile  Reply with Quote
quote:
Originally posted by Chicagogoat

I don't think there's many guys on this site familiar with M&H, but after trying the usual favorites I love 'em and am sold for life on these. They're very aggressive yet all around performers. All business no white lettering http://www.mandhtires.com/M-H-Drag-Tires/M-H-Drag-Radials/325-50R15#.UkT5sxDW6RM





That looks sweet!
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GtoGuy32
Cochise

USA
842 Posts

Posted - 27 Sep 2013 :  01:05:52 AM  Show Profile  Reply with Quote
Here's a pic of 275 60 15s on back 15x8 with 5" Backspacing. The space inside the wheel-well is about 1 inch on either side. No mods to the car.


Here's a pic of the BFGs



If I was home, I would take some better pics.

I corrected my post. The tires on the car are 275s, not 255s

Edited by - GtoGuy32 on 27 Sep 2013 11:05:23 AM
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Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 27 Sep 2013 :  09:57:42 AM  Show Profile  Reply with Quote
Look'en GOOOOOOD Guy's!


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Phil
The Great White Buffalo

USA
7214 Posts

Posted - 01 Oct 2013 :  3:28:35 PM  Show Profile  Reply with Quote
GTOguy, those MT's look great on that blue goat!

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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GtoGuy32
Cochise

USA
842 Posts

Posted - 02 Oct 2013 :  02:38:17 AM  Show Profile  Reply with Quote
quote:
Originally posted by Phil

GTOguy, those MT's look great on that blue goat!



Thanks Phil!
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Ponti350
Tribal Scout

Pakistan
2 Posts

Posted - 31 May 2015 :  04:24:29 AM  Show Profile  Reply with Quote
Hi All,

Your cars look epic!

Need to replace tires on my 72 lemans. Currently running 295/50/15 on speculated 9inch rims(will check and confirm). After a current ring and pinion swap to 4:11 the gearing is a bit too short on the 26.6 inch tall tires and frankly the old dunlops have little left to offer. The tire scrubbing factor is what is keeping me from locking in on ordering 275/60/15's.

I dont mind having to shave some of the inner lip if need be & will be putting fresh prothane bushings in the rear to help the matter.

Will the 275 work(not scrub) even if I go for 1-1.5 inch rear lowering springs (Need to get the control arms better aligned)

Appreciate your input.
Thanks Wyne.
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Chicagogoat
Cochise

USA
823 Posts

Posted - 01 Jun 2015 :  11:32:30 AM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
quote:
Ponti350 Posted - 31 May 2015 : 04:24:29 AM
Hi All,

Your cars look epic!

Need to replace tires on my 72 lemans. Currently running 295/50/15 on speculated 9inch rims(will check and confirm). After a current ring and pinion swap to 4:11 the gearing is a bit too short on the 26.6 inch tall tires and frankly the old dunlops have little left to offer. The tire scrubbing factor is what is keeping me from locking in on ordering 275/60/15's.

I dont mind having to shave some of the inner lip if need be & will be putting fresh prothane bushings in the rear to help the matter.

Will the 275 work(not scrub) even if I go for 1-1.5 inch rear lowering springs (Need to get the control arms better aligned)

Appreciate your input.
Thanks Wyne.


Yes, cutting the lip some is a common practice I've done myself. But if you're committed to fitting the widest profile back there. Then you may need a rim with more backspacing. A 295 or wider should have a 10" wide rim. I'm running 5 1/2" BP to fit 325/50R15's. But here's one more variable to complicate your decision. All manufacturers profiles vary a little to a lot as far as sizes with the exact same profile #'s. So check all published dimensions between manufacturers before making your decision.

Pure Pontiac: learn it, live it, love it!
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Chicagogoat
Cochise

USA
823 Posts

Posted - 01 Jun 2015 :  11:38:38 AM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
Here's a recent discussion regarding drag radials and sizes. Question, they have a lot of American classics in that part of the world? Either way, my hat's off to you for having a great taste in cars
http://psp.aquacomp.net/topic.asp?TOPIC_ID=9695

Pure Pontiac: learn it, live it, love it!

Edited by - Chicagogoat on 01 Jun 2015 11:39:48 AM
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Ponti350
Tribal Scout

Pakistan
2 Posts

Posted - 24 Jun 2015 :  03:15:29 AM  Show Profile  Reply with Quote
Thank you sir! There used to be predominantly american cars here in the 60's and 70's. Dodge had a plant here too. Not anymore.. mostly japs now.. but you'l find everything (true barn finds in our case).

From a model T to a new Nissan GTR and everything in the middle if you're willing to look. For American iron very few enthusiasts (predominantly restorers) and then probably just us running 350's and 454's (quarter mile - street)

Coming back to my question so 275/60/15's will work with a 1.5inch rear drop? Am running a Ford 9inch rear with a locker. I think 305 would be over-kill for now, Which brand are you running? For some reason Nitto 555R dont hook well here, i'm not expecting a dead hook either. (This is on the street in a BBC Nova)

Thanks Again Sir!
Wyne.
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Phil
The Great White Buffalo

USA
7214 Posts

Posted - 24 Jun 2015 :  07:20:51 AM  Show Profile  Reply with Quote
I have never cut the lip as you'll breach the welds between the inner fender well and quarter panel! (And give it a Rat Rod look in the process)
I "roll" it in ala Herb Adams handbook. I just put Scotch 33 electrical tape on it and use an adjustable wrench and a hammer (also taped) to work it a little at a time from @10-2 o'clock. Comes out great and then remove the tape and the paint is not all scraped up.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 24 Jun 2015 :  10:33:19 AM  Show Profile  Reply with Quote
Ratty rod. Set the frame on two 4x4's and build to that ride hight. Then on the body, use metal prep similar to case hardening on fire arms. Saw it on TV.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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