# 66 gto stock tire size??



## Mr66GTO (Nov 12, 2007)

What is the original tire size of a 1966 Pontiac GTO?? When i turn either left or right, my tire scrapes the inside of the fenders.


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## 68greengoat (Sep 15, 2005)

Everything I'm seeing is 7.75" x 14". Not sure what that width equates to in a new radial...


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## Too Many Projects (Nov 15, 2008)

68greengoat said:


> Everything I'm seeing is 7.75" x 14". Not sure what that width equates to in a new radial...


I believe the GTO's came with F70X14 on a 6" wheel. I know the 67's did, not positive on a 66. A metric equivalent is about P215-P225.


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## 68greengoat (Sep 15, 2005)

Too Many Projects said:


> I believe the GTO's came with F70X14 on a 6" wheel. I know the 67's did, not positive on a 66. A metric equivalent is about P215-P225.


For the life of me, I don't understand why they labeled the tires as 7.75" rather than F70. F70 we all understand. They were red stripe "premium" cord. Nothing but the best...


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## Too Many Projects (Nov 15, 2008)

68greengoat said:


> For the life of me, I don't understand why they labeled the tires as 7.75" rather than F70. F70 we all understand. They were red stripe "premium" cord. Nothing but the best...


The 7.75's came on the LeMans and Tempest. The F70 had a slightly lower sidewall with a tiny bit wider tread to give the GTO that "wide track" look....:lol: 70 series tires with bias-ply construction were cutting edge technology then. :cool


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## geeteeohguy (Feb 2, 2008)

7.75 x14 on the '66 GTO. The "70" series was not offered on the cars until '67. Then, it was the F70. Metric sizing was not really used until the early '80's, and prior to then, everything was inches. The standard tires on a lot of American sleds in the early '60's was a 6.00x14 or 15. Tall, skinny smoke bombs!!! A 7.75x14 is roughly equivalent to a 205/75/14 tire. Interesting note, John DeLorian was pushing like mad to get Michelin X radials on Pontiacs in 1965-66...he was shot down by the high brass. Just think how much further Pontiac woulod have been if that had happened....radial tires 20 years ahead of the competition!!!


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## 66tempestGT (Nov 28, 2009)

incorrect backspacing can cause this too if you have aftermarket wheels.


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## El Monte Slim (Sep 8, 2014)

*Tire brand(s)*

It's my understanding that although 66 GTOs came standard with 7.75 x 14 redline tires, you could order with whitewalls at no additional charge.

My question, if anyone knows, is this. Were all of the redlines supplied by the same manufacturer? Or were there multiple suppliers?

The "general knowledge" seems to be that they were supplied by U.S. Royal. Is that correct? Who knows?

Does anyone have a definitive answer?


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## GTOJUNIOR (Aug 7, 2011)

US Royal is all I've ever come across documented as OE on many original owner and/or "Survivor" cars.

I think a lot of confusion is the aftermarket was quick to get their offerings out and a lot of young owners switched to other brands.


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## geeteeohguy (Feb 2, 2008)

My '65 came with whitewalls and Custom wheel covers. A tripower/4 speed car, too. I have heard and read over the years that US Royal was the main supplier of the redline tires 'Tigerpaws'---- (not sure of the whitewalls). I have also heard that Firestone was used as a supply filler to keep the line moving. As GTO Junior said, the original tires came off the cars pretty quickly, but IMO, because they only lasted 15,000 miles at best. Back then, bias plies wore out about every two years for the average family. And, it was 50 years ago. But luckily, I still remember those days!


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