Biggest tires for my '68 GTO on 15" wheels... - Pontiac GTO Forum
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post #1 of 5 (permalink) Old 06-19-2019, 08:41 AM Thread Starter
 
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Biggest tires for my '68 GTO on 15" wheels...

All four new shoes are here and I have completely tested the fit. All is well!!! I can't imagine trying to squeeze in any more tire in the back or front. In the front with the wheel jacked and completely unloaded I turned her through the stops and had only one minor interference. It was in a condition that if I ever had the car in a situation where the wheel would see this state while driving... Tire rub would be the least of my concern. The rub happened with the passenger side at the front lip of the fender at the bottom corner. With the wheel completely unloaded and the steering turned to the stop, that fender corner touched the tire. Again... if I'm driving and have the wheel locked to the left and the wheel is completely unloaded something went horribly wrong.

The fronts are 235/60R15 wheels are 15"x8" w/4" B.S. Any more B.S. in the front with a 15" wheel and the wheel would be contacting the steering tie rod where it connects to the steering arm on the spindle. Any less B.S. and I would certainly be rubbing the fender in a couple places.

The rears are 295/50R15 mounted to 15"x10" Aero wheels with 5.5" B.S. The tires are about .5"-.75" from contacting the frame/inner wheel well with the wheel jacked up into the pocket to the point where the opposite wheel was lifted off the ground. Again, I feel I'm safe there. Also the rear wheel never came close to contacting the outer wheel/quarter lip. This new suspension (complete BMR package) helped a lot with this due to it be so incredibly stiff, even if the wheel was too wide I don't think I could ever load the rear wheel enough to raise it that high.

So a huge step forward and a huge sigh of relief. I was so nervous this setup wasn't going to fit and I would be stuck trying to sell them or make them fit somehow. I was prepared to roll the fender and/or rear wheel well lips but I am happy to report I did not need to do so.

FYI... the rear wheel/tires weigh 54lbs and the fronts weigh 47lbs.

[IMG]Untitled by paradox_69_666, on Flickr[/IMG]

[IMG]Untitled by paradox_69_666, on Flickr[/IMG]

[IMG]Untitled by paradox_69_666, on Flickr[/IMG]

[IMG]Untitled by paradox_69_666, on Flickr[/IMG]

[IMG]Untitled by paradox_69_666, on Flickr[/IMG]

Last edited by curtis.smith68; 06-19-2019 at 10:00 AM. Reason: Added wheel/tire total weight
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post #2 of 5 (permalink) Old 06-19-2019, 09:13 PM
 
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Looks good. What is the actual foot print on the front/rear tread?

Is there any difference in tire height as measured from the ground to the tread? Some tires get shorter as you go wider. Photo appears to show the rear tire a little shorter, but of course camera perspective/angle of the shot might be all it is.

You can go wider, but it may not fit neatly under the wheel well. I have the 15" x 10" wide for the rear and plan on the Hoosier 29" tall x 12.5" wide tire. Jacking up the rear end as needed for the tire fit and want it to hang out the wheel well for the look I am after.
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post #3 of 5 (permalink) Old 06-20-2019, 09:26 PM
 
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Is that a UMI powder coated red suspension?
Tires look great
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post #4 of 5 (permalink) Old 06-25-2019, 11:38 AM Thread Starter
 
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Originally Posted by PontiacJim View Post
Looks good. What is the actual foot print on the front/rear tread?

Is there any difference in tire height as measured from the ground to the tread? Some tires get shorter as you go wider. Photo appears to show the rear tire a little shorter, but of course camera perspective/angle of the shot might be all it is.

You can go wider, but it may not fit neatly under the wheel well. I have the 15" x 10" wide for the rear and plan on the Hoosier 29" tall x 12.5" wide tire. Jacking up the rear end as needed for the tire fit and want it to hang out the wheel well for the look I am after.
I have heard of some going a little wider than a 295. Where I am now, i couldn't get much closer to the inside but i do have a good .75" to grow on the outside. Originally I was looking at Hoosier DOT slicks but I figured I take the more practical rout for now. I am quite pleased with this setup and am glad I didn't go with the 6" B.S. on the rears.

This is a great site, if you've never used it before...

https://tiresize.com/comparison/

Granted it's based on nominal sizes. I have heard some people switching brands with the same tire size and having dimensional changes. Just like clothes... just because they list the size doesn't actually mean that's what it is if you put a tape measurement to it, plus wheel width plays a part in it too.

The rear tread measures out to be about 10.25 though it looks a bit wider than that, and the section width on a 10" wheel is close to 12". I'll get a picture with a ruler laying across them. The overall height difference from the old fronts to the new is a little off from what the tire size comparison site says it should be, by more than .5" but I think I can account for most of this in the fact that my old tires are bald lol.

So the new tires, front to back comparison per the site link above shows the rears to be .5" taller and 2.3" wider.
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post #5 of 5 (permalink) Old 06-25-2019, 11:40 AM Thread Starter
 
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Originally Posted by John Schutt View Post
Is that a UMI powder coated red suspension?
Tires look great
Thanks man! I went back and forth between UMI and BMR and ultimately chose BMR. It was basically down to a flip of a coin as they both make a superb product. I am extremely happy with the BMR complete suspension kit.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Wheels & Tires

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