68 69 GTO guys.. whats the widest wheels you can run without minitub? [Archive]

PT Goat

09-13-2008, 07:31 AM

17x9.5-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. Of course every car is a little different, and brakes change things, so measure carefully!

Roadbuster

09-15-2008, 11:19 PM

Mr. Vengence,

For clearance issues in the front the 68-69 GTO front fenders cut forward at the rear of the opening. This has caused me clearance issues with my current wheels and tires. Also there is a bubble protruding into the inner fender just above the center of the wheel. Why GM did this I don't know but again I have clearance issues with it. My current fronts are 17x8 zero offset with 245/45R17 tires.

At the top the wheel arch in the rear, I measured 13.5 inches from the inner edge of the wheel lip to the wheel house. This should allow me to run a 315 tire. This is my car with a friends 17x11 rim with a 315 tire on my car. I need a bit more offset than he has but that is why we did this test fit.

https://static1.pt-content.com/images/pt/2008/09/IMG_0050-1.jpg

I could gain some clearance by rolling the rear lip back to the trim maybe a 1/4 inch.

Jon

72 GOAT

09-17-2008, 05:14 PM

I have a 72 but I think the BS and widths are the same. I am running a 275-35-18 on a 18x9 rim up front and out back I am running a 295-35-18 on a 18x10. I have no rubbing at all. The front BS is 5.5 and the rear is 5.75.

andrewb70

09-17-2008, 08:29 PM

I run 295/40-18s on a 10.5 wheel with 6.5" backspacing. No rubbing.

Andrew

Grngoat

09-18-2008, 09:22 PM

Anybody try to fit 325-30-19s under one? I'd love to run C6 Z06 rubber all they way around my 70. There's not a lot of selection up over 300 mm.

andrewb70

09-19-2008, 04:43 AM

Anybody try to fit 325-30-19s under one? I'd love to run C6 Z06 rubber all they way around my 70. There's not a lot of selection up over 300 mm.

Not going to happen.

Andrew

Mr.VENGEANCE

10-15-2008, 08:41 PM

roadbuster

what suspension are you running?

Roadbuster

10-16-2008, 09:30 PM

roadbuster

what suspension are you running?

OK second try at this!

Vengence,
I have SC&C's (http://www.scandc.com) AFX kit with their upper and lower control arms and varishock coil-overs. Mark is a great guy to work with!

Out back I have a 65 rear axle and just got new springs and varishocks for the rear. I should be able to get them in this weekend. That should lower the back a bit and level the car out.

For pics see the build thread in my sig

Jon

Mr.VENGEANCE

10-16-2008, 10:02 PM

whoops!!!.. i got your screen name confused with code reds...

my bad.

Roadbuster

10-16-2008, 10:35 PM

no problem!

DriverzInc

10-17-2008, 11:24 AM

I'm a fan of the 17x11 rear with 315 wide tire, and 17x8 in the front. Popular wheels in these sizes are the Billet Specialties StreetLites that are on special this month from us.

Backspace is pretty standard for that car. 8's with a 4.75 and 11's with a 5.75" is what we've done.

TIRE FRYER

11-05-2008, 12:55 AM

hey roadbuster, why a '65 rear end?

Roadbuster

11-05-2008, 01:33 PM

hey roadbuster, why a '65 rear end?

A few reasons:

1. The '65 to '67 Pontiac rear axles are a little narrower than a '68 to '72 - one to two inches, depending on who you believe. Mine is 60.125 inches from wheel mounting surface to wheel mounting surface (drum brakes). I cannot run the 6.5 inch backspacing that andrew70 has on his car - the tires would hit the inside wheel house before the axle mounting surface. Less backspacing means more front space and a deeper dish on the same width wheel.

2. The '65 to '67 Pontiac rear axle uses a flat spring perch with a retaining cap and bolt to capture the bottom of the spring. The rear springs cannot fall off the car. This is an issue if you are running short springs and unload the suspension. Like going in a steep driveway at an angle or a Dukes of Hazzard stunt! The '68 to '72 uses an inverted cup to locate the spring and has no retaining bolt.

3. Two of them came with my car. :) A non posi in the car and an additional posi unit with axles but no brakes. Both have the same gear ratio.

I would advise anyone to measure (at least twice!) before you buy wheels. Especially if you are going for max width. I made a simple rig to take my measurements. I will see in a week or two when my new wheels come in how I did.

Jon

TIRE FRYER

11-06-2008, 12:21 AM

i am goig to get the strange s60 complete rear with baer rod & drag disc brakes. would it be wiser to get the shorter(older length) rear. i do not have wheels or brakes yet

Roadbuster

11-07-2008, 06:54 PM

i am goig to get the strange s60 complete rear with baer rod & drag disc brakes. would it be wiser to get the shorter(older length) rear. i do not have wheels or brakes yet

If you are going for custom wheels and want more "dish" then go for the narrower length.

I have wheels on order, so I will know soon about my own setup.

You could always order the rear to a custom very narrow width that clears the Baer E-brakes and would allow you to run wheels with the most "dish.

Jon"

Roadbuster

12-02-2008, 04:18 AM

My wheels and tires came in - 305/35R18 on a 18x11 rim

https://static1.pt-content.com/images/pt/2008/12/CIMG2053-1.jpg

Mr.VENGEANCE

12-02-2008, 06:07 AM

hay zeus..

Hellbound

12-02-2008, 07:09 AM

Nice fit !!

andrewb70

12-02-2008, 08:35 AM

My wheels and tires came in - 305/35R18 on a 18x11 rim

https://static1.pt-content.com/images/pt/2008/12/CIMG2053-1.jpg

Very nice! Once my Falkens wear out I may have to go with the Toyo 888s.

What size are you running in the front?

Andrew

Amatouring

12-02-2008, 07:31 PM

Roadbuster

12-02-2008, 08:38 PM

Very nice! Once my Falkens wear out I may have to go with the Toyo 888s.

What size are you running in the front?

Andrew

Hey Andrew,

I have 18x9 wheels with 255/35R18s in front.

Jon

andrewb70

12-03-2008, 06:57 AM

Hey Andrew,

I have 18x9 wheels with 255/35R18s in front.

Jon

Thanks Jon. When you get a chance I would love to see a side shot with the car on the ground, at ride height.

Andrew

Roadbuster

12-03-2008, 09:28 PM

Thanks Jon. When you get a chance I would love to see a side shot with the car on the ground, at ride height.

Andrew

Andrew,
Side shot the front wheel is turned a little to the left, so it looks further back than it is. Need to get better with the camera. :)

https://static1.pt-content.com/images/pt/2008/12/CIMG2052-1.jpg

I think I need to lower the front half an inch and dig out the front trim.

Jon

singer69

12-28-2008, 10:54 AM

Wow! My head is spinning with all the ideas I'm getting from this forum. Thank you all for the info! You guys are the best! I'll keep you updated as I progress.

Mr.VENGEANCE

12-28-2008, 11:55 AM

and it will only get worse my friend.. worse..

Roadrage David

01-14-2009, 07:41 AM

Marauder

01-14-2009, 03:24 PM

Andrew,
Side shot the front wheel is turned a little to the left, so it looks further back than it is. Need to get better with the camera. :)

https://static1.pt-content.com/images/pt/2008/12/CIMG2052-1.jpg

I think I need to lower the front half an inch and dig out the front trim.

Jon

Yeah, another 1/2" on the front may look good but be careful because when I lowered mine it tended to bottom out a lot in the front. I have the Hotchkiss "big block" springs but maybe they were the problem. Upgrading to QA-1 coil overs soon. The front wheelwell molding will look. Maybe even the GTO logo on the rear fender, the black would match the wheels....great looking car!

claytonisbob

01-14-2009, 04:02 PM

I know to fit 315's on the back of my 69 Chevelle (also A body) I went with a 6.25" BS. 5.5" definitly wouldn't have worked. Maybe GTO's have a narrower rear axle, or wider fenders, but if its what I think (close to the same), 5.5" would not be enough.

Roadrage David

01-15-2009, 12:46 AM

Who knows for sure?? befor i order...

Roadbuster

01-15-2009, 07:01 AM

SO what is the max i can put under my 69 GTO!!!.
i like to go 17x9.5 x 5.5bs up front, and the 17x 11 with 5.5bs ?? in the rear.
please advice a bit more.
im going to order al the stuff i need from Sc.c
i alredy got the hodkish frond and rear coil springs 2 and 1 /2 drop. the Metco billet alu Armsfor the rear. Helwig sway bar. polu bushing. i need upper and lower A arms Brake system, ATS spindle. 33/35 spline12 bold rear axer . VW V 48 rims + tires ecetera.

David,
I have 18x9 up front and 18x11 out back.

You will have problems with a 9.5 front. 68 and 69 GTO have a 'C' shaped wheel opening that cuts in at the back vs. the Chevys have a opening that moves away at the back. This cuts almost an inch off the width you can run. With 5.5 bs 9.5 wheel I think you will hit the fender. A 9 would be tight and you need to make sure your tire size is not too big. As you go lower you will have clearance issues with the inner fenders and the fender trim when you turn.

For the back, it is tight and might need a tweak, but they fit. I don't have a stock with rear axle so my back space will not help. Just measure it. I used a piece of scrap steel and cardboard to make a wheel template.

So 17x11 out back work, 17x8.5 will work up front, 17x9 is pushing it.

Jon

Roadrage David

01-15-2009, 07:53 AM

Thanks Jon!!!!!!!

Roadbuster

01-15-2009, 06:47 PM

Yeah, another 1/2" on the front may look good but be careful because when I lowered mine it tended to bottom out a lot in the front. I have the Hotchkiss "big block" springs but maybe they were the problem. Upgrading to QA-1 coil overs soon. The front wheelwell molding will look. Maybe even the GTO logo on the rear fender, the black would match the wheels....great looking car!

Hey Marauder, thanks for the compliment!:twothumbs It is now a half inch lower - easy with coil-overs - and I have the trim installed. Now the top of the front tires are just even with the fender well, but because of how they sit in the wheel well it matches the rear better. I will get some pics this weekend.

Jon

TIRE FRYER

02-19-2009, 07:12 PM

looks awesome roadbuster. any tire rub anywhere? also did you have to roll the lip at all or "massage" anything?

Roadbuster

02-20-2009, 11:03 PM

looks awesome roadbuster. any tire rub anywhere? also did you have to roll the lip at all or "massage" anything?

Hey Tire Fryer,

When I measured for the wheels I knew I had to do a minor tweak to the inner fenders near the rear due to the tire diameter. My thought when I set it up was that rubbing on the inside would not destroy the tire or cause a blow out. I also removed some thick undercoating in some spots.

I did not need to roll the lip, they fit without that. I still have my stock fender trim. :)

Now that I have driven it for a while I found it will rub on the inside if I try going in and out of some steep driveways that cause one wheel to really drop. In normal driving it does not. And I hope it stays that way! :fingersx:

Jon

inda_bebe

09-05-2012, 02:14 PM

David,
I have 18x9 up front and 18x11 out back.

You will have problems with a 9.5 front. 68 and 69 GTO have a 'C' shaped wheel opening that cuts in at the back vs. the Chevys have a opening that moves away at the back. This cuts almost an inch off the width you can run. With 5.5 bs 9.5 wheel I think you will hit the fender. A 9 would be tight and you need to make sure your tire size is not too big.

Running 18x9 wheels up front, what back space and tires are you using?

Sarge

04-01-2013, 07:01 PM

I have a 1970 GTO Project that I am trying to determine what is the widest wheel that I can put on the rear. I am wanting to know if a 19 X 12 or a 20 X 12 will fit on the rear? Do any of you know? I am considering the Boze Force Five Wheel. Thanks.

SShep71

04-13-2013, 10:30 PM

I think that you may have problems running a 12 wide on the rear. I remember talkin go the guys at drivers inc before everything went to hell about it and they told me 10 was the widest w/o mini tubs. I am in the process of ordering 20x10s rear and 19x8s front. The tire size is turning out to be a big headache as well. I am trying to figure out what is the largest tire I can run on the front for a 19x8 without running into problems.

TIRE FRYER

04-15-2013, 12:19 AM

NASH JUDGE

04-15-2013, 05:48 PM

https://www.pro-touring.com/showthread.php?71318-Super-big-thanks-to-intro-wheels&p=854539&highlight=#post854539

Roadbuster

04-21-2013, 10:50 AM

Roadbuster seems to have good success with running an 11 inch in the back of his, as I am going to do with mine. I have the same width rear as his car and I just got to that part of my project. I just got the wheelworks tool and am gonna start measuring soon. I think I'm gonna go with Rushforth, as he has been the most responsive of all the custom wheel shops. None of the shops seem to want to take the car in and measure and goof up, so I'll have to do it. Keep the posts coming, and Ill put pics and info up soon as I get them.

Hey Tire Fryer! PM if you want some help. You aren't too far from me.

I recently upped the sizes on my 68. 275/35R18 fronts on 18x9.5 and 315/30R18 on 18x11 rears. Check out the RTTC photo thread from earlier this year. That is the best photos of the car with these tiers.

Without body work that is the widest to fit in the rear. There is very little clearance.

TIRE FRYER

05-25-2013, 02:22 PM

Awesome. Thanks!

the450r

03-26-2014, 10:51 AM

I am also trying to upgrade wheels and tires for my 68 GTO. Ive been told by several of my friends not to get 18" wheels. 18s seem to have more tire size choices and 17s wheels and tires are cheaper. I am still undecided on rim size. I have found the rim I like and they are available in 17x8 17x9 and 18x8 and 18x9. 9" rim 8mm offset or 5.25 bs and the 8" rim 4.5bs or 1mm.
my car is very low with 245/60/15 rear and 235/60/15 front. with lots of room all the way around the tires. I was looking at 275/40R17 on 9in wide rim all the way around but they are shorter than what I am running now that will make me closer to the ground and less tire in the wheel well. 275/40R18 are the same in height but probably looking at front fender rub issues.

I have SC and C suspension. tubular lowers and adjustable uppers. stock spindle with stage 2 plus ball joints. factory style disc brake conversion. hellwig front and rear pro touring sway bar. SPC lowing springs. PMT rear control arms with a 9 inch quick performance rear end stock 68-72 chevelle gto width.

I need help.
What do you guys think? thanks in advance

TIRE FRYER

07-17-2014, 12:16 AM

the450r have you made any progress yet on wheel selection? I just fired up my car and it runs, so working on wheel offset next. Want to stuff a 3 series rear tire in the stock wheelwell.

the450r

07-17-2014, 08:00 PM

I bought 275/40/17 nitto nt05 on 17x9 wheels with 5.5 bs on all four corners. Looks awesome. A 285 might fit but like roadbuster says 315 will run with a watts link to keep the frame centered over the axle.

TIRE FRYER

07-29-2014, 08:12 AM

Looks sharp! Looks like there is still lots of room for more tire in the back. I'm gonna start measuring soon for offset, looking for a junk/used 305 or 315 tire to measure with. I did have my fenders rolled before the car got painted. I also have the shorter pre 68 rear axle like Roadbuster.

the450r

07-31-2014, 02:40 PM

Roadbuster said a 285 would fit but anything bigger would require a watts link to keep the rear end centered and away from the body roll in turns. A friend has 295 on 15 rims and they rub if people sit in the back or turning aggressively with factory suspension and ride height. The shorter axle vs the wider one doesnt allow bigger tires but it does require custom off set so a bigger lip and zero or negative offset is needed. It looks cool but the more wheel hanging off the more stress on wheel bearings axles and wheel studs. ( think of mounting a normal wheel on backwards) 17x9 wheels and 275 tires are priced right for me. The wheel house is even with the frame so serious fab is needed to "tub"

302J-Code

10-02-2014, 10:21 PM

Bump.

Currently in the process of ordering new wheels and tires for a 69 GTO
I have used the search button and read a lot of threads I just need a for sure answer before I order.
Stock Rear End

18x9 w/ 5.5 bs
275/35/18

18x10 w/5.75
295/35/18

Is this the Absolute widest I can go without running into issues?
Do I have the correct BS?
Can I run a 305 or 315 in the rear?

Any other suggestions or comments will be appreciated

Will roll the lip if I have to.

Car will be lowered 1"-2" all the way around in the future.

Also installing a Watts Link Next Week.

103608

103609

103610

THANK YOU

the450r

09-18-2017, 10:10 AM

I get asked alot what's the widest tallest tire to run on a 68/69 GTO. Just looking at tire sizes. Not alot of 305 options I found bf Goodrich rivals in that size. I don't think with stock suspension it's possible. Any 275 on front require sc&c suspension. Don't know anyone else running that much rubber up front without a Aftermarket frame.

TIRE FRYER

01-09-2018, 01:43 AM

Have you tried anything yet? I'm about to measure up for a set of wheels.

boss_hoss

05-07-2018, 12:07 PM

I'm running Mickey Thompson street comp tires on Foose legend wheels. 245/40r18 on the front and 305/35r20 on the rear. Rears fit pretty tight but I'm planning on rolling the inner lip to get a little more clearance.
152254

USAZR1

05-07-2018, 05:10 PM

boss_hoss

05-08-2018, 02:58 PM

What width rear wheels do you have? What backspacing?

20 x 10 wheels Offset: 0 BS: 5.5

USAZR1

05-08-2018, 05:33 PM

20 x 10 wheels Offset: 0 BS: 5.5

Yeah, a little more backspacing might've helped. On my 70, I've got 20x10's w/5.75 bs (+6 offset) and 305/30/20 Nitto 555 G2's on the rear.

boss_hoss

05-08-2018, 07:28 PM

Yeah, a little more backspacing might've helped. On my 70, I've got 20x10's w/5.75 bs (+6 offset) and 305/30/20 Nitto 555 G2's on the rear.

Thanks for the info, After looking at it you're definitely right. There's plenty of room to the inside. wonder if a machine shop could mill the mounting face down a bit to get me some more clearance.