[Allen Polmann]

Hi All,

This is my 1st attempt at this so here goes!

I have a 1971 GTO and I need to know what the max tire diameter, sectional width and height is before tire rub occurs.

My car body is not modified in any way. I got lots of conflicting answers.

The reason is I really like the NITTO tires (NT-455R or the NT-05) but they only have tires for 17-inch rims and higher. Going to a larger size 17-inch rim also increases my new rim selection.

Thanks for your help!

Allen

[oakster]

I run 275/60/15 on my 71 but I like the old school look

[Allen Polmann]

Hi Oakster,

So the 275s will fit the rear! What do you run in the front?

Thanks

[Allen Polmann]

Hi Oakster, Forgot to ask about the back set, is it 5.5 for the 275s?

[oakster]

I run 235/60/15 up front. Not sure of the back spacing. Someone might weigh in on that. My cars are @ my other garages right now so I can't check

[Allen Polmann]

Thanks Oakster, very much appreciated. It's great to talk with real Pontiac guys and get accurate information!

Allen

[A.W.Dille]

I'm also running 275-60-15's on the rear of my 71 also on 15x7 Ralley II's. On the front I'm running 225-70-14's on 14x7 Ralley II's. Plan on going with American Torque Thrusts (old style) sometime in the future. I'm old school also so the classic look always appealed to me.

[nkowi]

Not only will 275s fit, they fit with room to spare. 285s would be a non-issue as would, I expect, 295s.

Sorry, I can't recall the offset of my wheels, but they're 18 X 9.5.

[Loffen]

Allen !

Welcome to the forum

[Allen Polmann]

Hi Guys,

I would like to thank everyone for such rapid responses and now I have the info I need.

Don't worry guys of the old school, I wanted to go with larger 17-inch rims simply because of the NITTO tires I want. I will remain old school with my rim selection being American Torq-Thrust D.

The last question is if I go with larger tires/rims in the rear and smaller in the front, this will impart a slightly downward angle toward the front, will this have any repercussions on handling or stress the front end during cornering, low and/or high speeds? The entire front end is completely rebuilt but I only have a stock suspention.

Thanks for all the help.

Although this is my fist car, I will try to pass on what I'v learned to try to help pthers filter through all the noise out there!

Allen

[Evil Stu]

Originally Posted by Allen Polmann

Hi Guys,

I would like to thank everyone for such rapid responses and now I have the info I need.

Don't worry guys of the old school, I wanted to go with larger 17-inch rims simply because of the NITTO tires I want. I will remain old school with my rim selection being American Torq-Thrust D.

The last question is if I go with larger tires/rims in the rear and smaller in the front, this will impart a slightly downward angle toward the front, will this have any repercussions on handling or stress the front end during cornering, low and/or high speeds? The entire front end is completely rebuilt but I only have a stock suspention.

Thanks for all the help.

Although this is my fist car, I will try to pass on what I'v learned to try to help pthers filter through all the noise out there!

Allen

Here is a 70 with 275/40/17 on American Racing 200s. 17 x 9.5 with 5.25" backspace. The front fit is really good, if you wanted you might even get more rubber in at the rear depending on just how carefully you measure. 315/35/17 is possible on an 11" wheel if you trim the lip.

[Steve Barcak]

I've run 295/50-15s on 7" and 8" rims now for over 30 years on a half dozen '70-'72 GTOs. I run 265/50-15s on the front.
Have always like lots of rubber under my GTOs, looks and handles great. The 70-72s have more tire room than the older GTOs.

[Steve Barcak]

Here are some pics I dug out to show you.
These are 295/50-15s on 8" rims on the back of my '72 WW5 300,000mile GTO. This is the only rear tire size I have ever used on it since I bought the car in 1984 ( other than snow tires in the winter for ski trips ).
I think they look great and would never run smaller rubber. It is just my preference and think, besides better cornering, it looks more aggresive and sure footed. Not sure why I seem to be the only one who thinks this way.? It seems everyone else likes smaller tires.

[Steve Barcak]

Here are a few more. Just trying to give you an idea of how nice these cars look with lots of rubber.

This pic is in Ohio while on the road. Part of an 11,000 mile road trip made with this car over 7 weeks.



This pic is in West Virgina, beautiful country! the memories will last a lifetime. I disconnected the trailer for this picture. I just love the looks of these cars! esp without the added on wings, stripes, etc. they are so clean looking without the clutter IMO. I've driven these cars all my life and will continue to do so for whatever time remains of me. They are just beautiful and very nice to drive.

[Allen Polmann]

Hi Evil Stu,

Nice GTO! So you are running 275s in the front too? WOW didn't think that would work in the front!

Hi Steve, Your car actually looks good with the larger tire size. You have even larger tires in the rear than I though would fit. What is your back space for both rims?

You don't have any rubbing problems during sharp turns? Any handling problems at higher speeds due to the declined angle in the front?

Thanks Guys, much appreciated

[Steve Barcak]

Tires do not rub at all. I am pretty sure the factory 15 by 8 snowflakes have a 4" backspacing.
For a time, I ran 295/50-15s on all 4 corners! No rubbing issues that way either. However, I decided I preferred a size smaller on the front so, have since gone to a 265/50 on front.
Note- I am running disc brakes at all 4 corners on this car. The added thickness of the rotor coudl have made it rub on the outside. So, on this car, I am using an early '65 era 12 bolt housing which is an inch narrower than the '72 version. With that narrower rear, my tires have plenty of room. Even while towing with a full tank and friends in the back seat- no rubbing.
With the standard drum set up in the rear, I have still successfully ran this same tire/wheel combo with no issues. Cannot see you having an issue if I am not. There may even be room for more rubber but, at the time Dunlop, my preferred brand choice, only offered as big as 295/50. As you may or may not know, Dunlop has discountinued the tires I use. When I learned of this, I seached the US and bought some extras because I like them so much. So, I do have several thousands of miles left to use these sizes. When they wear out, not sure what I will do.
I really like the look of the 17 by 9 Snowflake that Year One makes and may try those down the road if I cannot find a wide enough 15" wheel to my tastes.

My WW5
GTO is not as pretty and perfect as many who post on here but - it is a real driver and still is very presentable and I can, and do, drive it everywhere- rain, snow, mud, towing, etc. I just love driving it and plan to have it back on the road sometime this year. Am putting together and other engine for it. The engine ( shortblock ) that was in it lasted 181,000 and is now going in my '61 Safari!
It will have another 455 2 bolt short block with original top end and tri y headers. The original standard bore block is in storage to install if I ever decide to restore it. She'll get another top coat of paint as well but retains most of her original sheetmetal and exhaust, all of her floors etc.
Oh, the pleasure this car has brought me for close to 30 years never seems to die out. No other car has been as satisfying to drive and life is too short.

[Evil Stu]

Originally Posted by Allen Polmann

Hi Evil Stu,

Nice GTO! So you are running 275s in the front too? WOW didn't think that would work in the front!

Yes, on all 4 corners. Lots of room left for more at the back. I ran 295/50/15 rears on the original rally 2 wheels for years. (15x7 w/ 4.25" BS), never an issue. When that size became unavailable I used 275/60/15 and then went to the 17" wheels.

[Allen Polmann]

Hi Steve,

I love your GTO passion. It doesn't really matter if she's not a show room car, you enjoy driving her and that's all that counts! Thanks for the follow up!

Hi Evil Stu,

OK Now I've got some real decisions to make on the tire sizes. So many said that these sizes would never work on my 71 GTO but I see the pics that say otherwise.

I'm really liking this Pontiac forum. Thanks

[DRI]

Hi Allen.
Here's my 70 with 255/60/15 on the front 1" drop and 275/60/15 rears 1/2" drop.All on stock 15x7 rally's. No rubbing on the fronts but I think the rear needs to come down.

[Allen Polmann]

Hi DRI,

Looks good!