# 65 GTO 15" Biggest Rear Wheel and Tire Recommendation



## McManusGTO (Dec 18, 2020)

HI Folks,

If you could recommend biggest 15" Rear Tire & Wheel combination for my 1965 GTO? 

Look for the widest, fat rear end look without modifying the rear fender lips.

Thank you in advance.


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## Baaad65 (Aug 29, 2019)

I have 275/60/15 MT drag radials on 15x8 rim's on my '65 with 3/4" spacers under the stock springs and it's tight but no rubbing on bumps, like the stance without the spacers but the tires rub on larger bumps so when I get it painted I'm going to have them make some more room in the well. Would someday like to run 17" so it looks more modern.


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## McManusGTO (Dec 18, 2020)

Very nice!

It looks like you could fit a wider tire from the pics. 

Fontaine Blue?


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## McManusGTO (Dec 18, 2020)

4.5" backspacing ?


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## Baaad65 (Aug 29, 2019)

Thanks, some GM color I got it that way and love it, guess it was red originally, I think 4.5 or 5 what ever it shows on the American Racing site.


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## Baaad65 (Aug 29, 2019)

I wish, I already ground the wheel well trim back to quarter lip.


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## McManusGTO (Dec 18, 2020)

Baaad65 said:


> I wish, I already ground the wheel well trim back to quarter lip.
> View attachment 143229


I see it now, its close to the lip.
I wonder if 5" backspaced wheel would have helped?


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## Baaad65 (Aug 29, 2019)

Idk because there's only maybe an inch on the inside from tire to frame, and idk if there was a choice on the MT website but these were the most popular setback and got them through Ebay...I didn't know how to check setback and my tire person wasn't much help, he said to buy 255 that 275 would never fit so that's what bought first then when we mounted them he says I could've went bigger, I wanted to strangle him because then I couldn't return the tires after they been mounted so had to sell them for half and bought 275. Then when you installed the 461 the Sportsmen's had no traction so changed them out again to the drag radials and giving away some more tires, I'd really like 17" but the tires are slightly larger and they reccomend a 9" rim over my 8"s so they would never fit until I make some room in the wheel well but maybe with a 5" setback it's a possibility I just need a good way to measure things and a bunch more money...I'll work on making these tires bald 🤣


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## Baaad65 (Aug 29, 2019)

Anybody out there have 17" wheels on their goat and what size tires especially for a '65? Like to do the front too but got to watch the clearance as I'm running 215/70/15 now with 1" in lower springs and the just clear everywhere even on big dips and bumps. Guy that did my alignment said wider tires up front would wander...you know I just kinda didn't put a lot of thought to sizes as I just got back into the game after 30 years on the sidelines and thought 15" was a big upgrade from 14" but after a couple years going to shows my 15" tires look like balloons but I'm not crazy about the 20" and up look on 60's cars. I want to stick with the same wheels and they only come in 15" and 17".


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## Baaad65 (Aug 29, 2019)

Here's a couple more pix to show what I'm seeing.


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## McManusGTO (Dec 18, 2020)

Gorgeous!


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## Banjos (May 10, 2021)

I don't remember the size of rear tire that was on the car when I bought it (mid 2000's).... but these are balloons (not photoshop!) 









I quickly changed to 215/60R15's. I like the look of stock size tires.


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## PontiacJim (Dec 29, 2012)

If you jack the rear up a bit, you can go wide and not have to modify wheel wells.


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## Baaad65 (Aug 29, 2019)

Blast from the past but I'm trying to get the rear end down 👍


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## McManusGTO (Dec 18, 2020)

PontiacJim said:


> If you jack the rear up a bit, you can go wide and not have to modify wheel wells.
> 
> View attachment 143318
> View attachment 143319


The good ole Days!


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## Mine'sa66 (Oct 30, 2019)

275/60/15 on 15x7's with 4.25" backspacing;


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## McManusGTO (Dec 18, 2020)

Mine'sa66 said:


> 275/60/15 on 15x7's with 4.25" backspacing;
> View attachment 143354


Beautiful GTO!

I was going to go with 15 X 8 rear rims.


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## PontiacJim (Dec 29, 2012)

McManusGTO said:


> Beautiful GTO!
> 
> I was going to go with 15 X 8 rear rims.


15 x 8's were a fairly standard rim used back in my time. The key is the tire size. You will have thread width BUT the thing you want to know is sidewall width. Example, you can have a 9" wide tread width and 11" wide side wall section.

Most tires will have a recommended rim width range. The width of the rim seems to be what affects the section width, not the tread width as that always stays the same. This is why you see some of the contemporary cars/trucks with funky looking sidewall bulges as they purposely get rims/tires to make this look. From my researching, you don't want a rim too narrow for a wide tire as the narrow rim will draw the sidewalls/tire bead way in (like squeezing it together) and the angle that the side wall will take as it rides on the rim can become too excessive and the rim can over time cut into the sidewall at the bead rather then the bead/sidewall ride in a more vertical position where the rim won't be grinding/cutting into it as the tire flexes about - or possibly slip on those really good traction days.

The Metric tires are rated a bit different than in my time, so just try to get your tread width, section (sidewall) width, tire height, and recommended rim sizes. Keep in mind that tire size changes (height) can affect your speedo accuracy.

If your suspension is worn, side-to-side play that will affect axle centering should be thought about. The rear-end will move/shift about as the car goes down the road, so allow room for this. In my experience, most of the rubbing, if any, seems to be in the wheel well due to its shape. Weak coil springs will have the car moving up and down and you want to take into acount any hard bumps that may cause the suspension to bottom out and put the tire higher into the wheel well when it does.

You may also want to google Chevelle of the same year as they would be a similar fit.


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## McManusGTO (Dec 18, 2020)

PontiacJim said:


> 15 x 8's were a fairly standard rim used back in my time. The key is the tire size. You will have thread width BUT the thing you want to know is sidewall width. Example, you can have a 9" wide tread width and 11" wide side wall section.
> 
> Most tires will have a recommended rim width range. The width of the rim seems to be what affects the section width, not the tread width as that always stays the same. This is why you see some of the contemporary cars/trucks with funky looking sidewall bulges as they purposely get rims/tires to make this look. From my researching, you don't want a rim too narrow for a wide tire as the narrow rim will draw the sidewalls/tire bead way in (like squeezing it together) and the angle that the side wall will take as it rides on the rim can become too excessive and the rim can over time cut into the sidewall at the bead rather then the bead/sidewall ride in a more vertical position where the rim won't be grinding/cutting into it as the tire flexes about - or possibly slip on those really good traction days.
> 
> ...


Jim,
Thank you


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## Baaad65 (Aug 29, 2019)

Good information, I'm running 8" rims in back 7" up front, if I want 17" rims the only 28" tall ET SS drag radial recommend a 9" rim and the tire would be a 305/45/17 pretty big and I would definitely need some wheel well massaging but I want to stay with 28" tall so my rpms don't get any higher at highway speeds.


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## Mine'sa66 (Oct 30, 2019)

McManusGTO said:


> Beautiful GTO!
> 
> I was going to go with 15 X 8 rear rims.


I would.
The only reason I have 15x7's is because at first I put 2456015s all the way around. Then I did my disc brake conversion, which widened my track by about 3/16" causing the fronts to rub. So I dropped to 2356015. Then I put a 12 bolt in with 3:31's and since now I didn't have the 4 the same size look I wanted, I went with the biggest I could on the back.


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## Bigfoot1965 (Mar 25, 2021)

I wanted the same look your talking about, and I went with 15/8 Weld Racing wheels with 4.5" back spacing, with Mickey Thompson ET Street Radial P255/60R15s. I bought them while I still had the body and frame separated. I measured everything 6 ways to Sunday, and I should have an inch clearance inner and outer. I'm still in paint and assembly mode, so the suspension hasn't settled yet. I put 15/4 Weld Racing wheels on the front, with Mickey Thompson Sportsman Radial 26x6R16LTs.
I'm guessing you've already researched it, but Eastwood has a device that will roll the lip to help with clearance. IMHO that would be more desirable than grinding the lip. Go to their site and search for Fender Roller. I'll be considering this if I find my measurements were off.


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## McManusGTO (Dec 18, 2020)

Bigfoot1965 said:


> I wanted the same look your talking about, and I went with 15/8 Weld Racing wheels with 4.5" back spacing, with Mickey Thompson ET Street Radial P255/60R15s. I bought them while I still had the body and frame separated. I measured everything 6 ways to Sunday, and I should have an inch clearance inner and outer. I'm still in paint and assembly mode, so the suspension hasn't settled yet. I put 15/4 Weld Racing wheels on the front, with Mickey Thompson Sportsman Radial 26x6R16LTs.
> I'm guessing you've already researched it, but Eastwood has a device that will roll the lip to help with clearance. IMHO that would be more desirable than grinding the lip. Go to their site and search for Fender Roller. I'll be considering this if I find my measurements were off.
> View attachment 143360


Do you believe that a 275/60/R15 with 4.5" backspacing would work?

I am in the same mode as you are....getting ready for paint and re-assembly.

Your car looks great...she will be beautiful when finished.


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## Baaad65 (Aug 29, 2019)

Did you get a pre '68 or '67 I believe 12 bolt because I remember the '65 rear is 1" narrower and that will give you clearance problems also I ground the wheel well trim down to the actual well about an 1/8" ,every little bit helps but I'm having clearance issues up higher in the well where it bumps out and there's two layers so I'd like to have that heated and planished in some when I get it painted then I can take the 3/4" spacers out and it looks good but like I said it will rub on good bumps. I'll have to check out the setback or offset of mine and maybe changing that would help, American Racing has a good measuring guide on their site...still like the look of 17" wheel on their visualizer.


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## Bigfoot1965 (Mar 25, 2021)

I don't know. The dimension you should be looking at is the section width, which should be the measurement from sidewall to sidewall. If you go to Jeg's website and enter 672-3452, you'll see the tires I bought. Scroll down to the details and it shows the section width as 10.2". Do the same thing with 672-3453 and the 275s will come up. The section width for the 275 is 11.1". That's a little too close for me to take the chance.
Thanks for the compliments! My car is going to look even better when I pop the hood. Check this baby out. 1972 455 HO, 7F6 heads (round port), solid roller cam, roller rockers, dual quads. Built to put out more than 500 hp. Can't wait to hammer down on that baby!


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## Baaad65 (Aug 29, 2019)

Very nice !...throw back wires too, these cars just weren't made for big meats that's why I'm surprised 275/60/15 fit with just a 3/4" spacer on stock springs. Here's a couple more pix for a visual and believe it or not these two pix were taken within minutes so I don't know why the rake looks so different probably my camera angle 🤨


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## Bigfoot1965 (Mar 25, 2021)

That's a great looking goat! I'm hoping to get mine on the road this summer. So much to do, most of which I've never done before, but that hasn't stopped me yet!


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## McManusGTO (Dec 18, 2020)

The GTO I have been working on weekends with my brother-in-law since last December.


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## McManusGTO (Dec 18, 2020)

As you can see, I have more room with the current rear 255/60/r15 tire/rim combo.


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## Baaad65 (Aug 29, 2019)

Yup you sure do and I did 1" performance lowering springs in the front and love the front stance....yours is looking great 👍


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## McManusGTO (Dec 18, 2020)

and the beast that lurks within....


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## PontiacJim (Dec 29, 2012)

McManusGTO said:


> View attachment 143397
> 
> 
> and the beast that lurks within....


Gotta put some semi-gloss black paint between the fins to bring out those MT valve covers. My engine will be Ford blue because I like it much better than the Pontiac colors. So my finned valve covers got the treatment.

This is where I left off on my build, but this is about the stance I want. It'll sit high in general, with a little more at the rear. Should be able to drop the transmission or change a clutch without needing a jack to get it up high enough. Those prone to nose bleeds might want to refrain from riding along. LOL Got Hoosier 29" x 12.5" x 15" tires and 15 x 10" rims that will go out back.


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## McManusGTO (Dec 18, 2020)

Jim,

In your honor for all you do on this site, the MT covers will be polished up, sprayed blue in between the fins and will have someone engrave "Pontiac Jim" on the flat section of the covers.. I am focused on finishing the body work and get her painted. I will have her in epoxy primer by EOD tomorrow.

The 722 Ram IV heads are the cats arse!


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## BearGFR (Aug 25, 2008)

Be aware, it's dangerous to try to push the limits on tire fit based on the advice or experience of others. Not because they're "wrong", but because of variances from one car to the next. Keep in mind these things were built on an assembly line by people in a hurry, who might have been hungover or thinking more about the weekend than their job, so the body to frame fitment varied. As long as they could start the bolts, it was good. Also there could have been prior collision damage.

The only way to know for sure what will fit on your car, is to measure your car. There are tools that can help.

Bear


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## Baaad65 (Aug 29, 2019)

This has really gotten serious 👍...here's my two cents on what I wanted on my valve covers for what it's worth.


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## Baaad65 (Aug 29, 2019)

But all kidding aside I'm just an amateur these other guys are the pros that's why I follow them 👍


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## McManusGTO (Dec 18, 2020)

Baaad65 said:


> This has really gotten serious 👍...here's my two cents on what I wanted on my valve covers for what it's worth.
> View attachment 143403
> View attachment 143404


My Lord...detail, detail, detail.
Beautiful work of art.


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## PontiacJim (Dec 29, 2012)

McManusGTO said:


> My Lord...detail, detail, detail.
> Beautiful work of art.


Ya, but you won't see that kind of beauty out of an LS swap. Our engines are a work of art. I'll hold you to the MT valve cover make-over!  Do you want a photo of me as you may want to laser etch it in on that flat section along with my name.........and it better say "Dedicated To" and not "In Memory Of,"..........LOL.


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## Baaad65 (Aug 29, 2019)

McManusGTO said:


> My Lord...detail, detail, detail.
> Beautiful work of art.


Thanks, and don't tell anyone but I used AMC engine blue because it went better with the car color.


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## Baaad65 (Aug 29, 2019)




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## McManusGTO (Dec 18, 2020)

DP 50LF Epoxy Primed 

Getting closer...


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## Baaad65 (Aug 29, 2019)

Are you painting it yourself? and in the previous picture is the motor installed because it looks like you can lower the front some, the front wheels and tires look good. I almost went with Centerline wheels but everyone else said they liked the more nostalgic look and I agreed once I got them but it was a hard decision then I had the rims redline striped and found some Pontiac bubble decals for the center caps because I like nostalgia 👍


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## McManusGTO (Dec 18, 2020)

Baaad65 said:


> Are you painting it yourself? and in the previous picture is the motor installed because it looks like you can lower the front some, the front wheels and tires look good. I almost went with Centerline wheels but everyone else said they liked the more nostalgic look and I agreed once I got them but it was a hard decision then I had the rims redline striped and found some Pontiac bubble decals for the center caps because I like nostalgia 👍


Yes, going to look her over carefully see what I missed...fix a few dings, re-epoxy prime those areas, then PPG 2K, sand with 600 grit, and prep her for base coat/clear coat. Will take the front apart next weekend, clean up and paint the firewall, under hood, frame and radiator support. The underbody is partially painted with POR-15 and I will complete the remainder in the coming weeks. Next.. re-assemble, tape everything up and begin the Base Coat/ Clear Coat process. Picking something around a Fontaine Blue is my next quest. She does not have the original engine or transmission, not going for an "All Original" car. She was an old drag car that sat for many years and want to keep with the history. She may have spent time at Dover Dragway https://doverdragstrip.com/


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## JaguarXJ6 (Jun 23, 2021)

Thanks Baaad65, your front and rear tire sizes have helped me figure out how to get some decent diameter matched rubber on 15' Rally IIs without having to force an upgrade to 17" Rally IIs.


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## McManusGTO (Dec 18, 2020)

I spent soo much time in this trunk, spatter painted it this past weekend. Getting ready for the 2K this weekend and hopefully painting the goat next weekend.


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## Imposter (Jan 3, 2020)

what belt setup is that


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## Baaad65 (Aug 29, 2019)

On my car? CVF Racing


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## Baaad65 (Aug 29, 2019)

So going back to this thread has anyone tried putting a 305/45/17 on a '65 gto in the rear? I have 15's and want to upgrade to '17's keeping the same American Racing VN501 wheels but the only American drag radials that are still close to 28" tall are the 305's. My rims have a 4.5 backset and I have 1" of space before interference towards the inside so I can get a 17 x 9 with a 5.47 backset. If I go with the 275/45/17 the tire height drops almost two inches and will produce higher rpms, I'm already at 2400 rpms @ 60 mph. I wish there was a way to try tires and rims on so I don't have to take chances buying then not being able to return things. I do have a measurement guide I'm going to try. The fronts are working out going with an 8" wheel and a 235/45/17 Firestone Firehawk 500 that's just a little shorter than my 215/70/15's


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## Baaad65 (Aug 29, 2019)

Also I shouldn't have said the fronts are taken care of, I need to see if 245/45/17's would fit then I could stay with Mickey Thompsons all around but I have 1" lowering springs and a 1 15/16" anti sway bar with generic Chevelle disc brake calipers, I can get the 8x17" wheels with a 4.5" backset but not sure if a 245 is going to be to big if so I have to find a different brand of tire as long as it's an American name...don't really want Nitto's or something foreign on my American muscle car but that's just me.


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