[Blued and Painted]

Mr b-man,You did say truck rims. Bean counters run the show. I don't think it would be the first time GM shorted the consumer.

NotaT/A, Are those steel wheels and is it a special addition model?

goatless, Great video's. Looks like no driving around the water box at Atco.

[Steve C.]

"This calculator said 10.8" wide. 28" tall"

Sorry for the confusion, I was thinking you wanted the "tread width".

The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".
.

[hada76]

Originally Posted by NotaT/A

It seems that GM is ok with a 275/60-15 on a 7" wheel. They have done it on several truck applications.

See attached tire placard

I remember when these first came out, they had huge factory rubber

[The Champ]

Originally Posted by b-man

Interesting that the engineers at General Motors thought that a 7" wide rim would work fine.

But what do they know ?

That was in 1989.

Maybe GM and the tire industry learned of possible dangers over the years.

I remember Ford thought that 26 pounds of air in an Explorer was "safe" at one time too...

[NotaT/A]

To BluedandPainted's question, yes, they are steel, and no, it wasn't just for special editions. If you chose the sport option on the GMT400 you could get that tire/wheel combo. I'm not sure of the first/last years of that option, but it ran through at least the mid nineties.

I did check the 2014 TRA yearbook today, and their recommendation for a 275/60-15 is a J wheel of 7.5 to 9.5 inches wide. Perhaps the JJ flange specified in my previous post is what made it work with a 7 inch wheel. It could have even been a deal where GM worked with BFG on the OEM tire construction to make it work out.

I'm not saying to put a 275 on a seven inch wheel, I'm just pointing out that it was an approved combo in certain circumstances. And yes Champ, things have changed in the last 25 years or so, but the OP was asking about a combo for a 40 year old car, so I thought my initial post might be relevant to the conversation.

In the end, you need to make sure to use a wheel width approved by the manufacturer of your tires.

[The Champ]

Originally Posted by NotaT/A

In the end, you need to make sure to use a wheel width approved by the manufacturer of your tires.

And, to the best of my knowledge, there is not currently a 275/60/15 on the market that has a 7" rim listed as an acceptable rim...

[goatless]

Originally Posted by The Champ

And, to the best of my knowledge, there is not currently a 275/60/15 on the market that has a 7" rim listed as an acceptable rim...

Nor was there ever a 1964 GTO that was designed to be run with 15" rims and radial tires. You know you're taking your life into your own hands every time you get in that death trap.

[NotaT/A]

Just for fun I checked with Discount and Tire Rack. Both suggest a 7" wheel with a 275/60-15. They also have 8", 8.5" and 9" as recommendations, but they recognize that people may want to stay with what they have.

From: http://www.tirerack.com/upgrade_gara...=wheels#wheels

SIZE: 15x7
American Racing AR767 Steel Black Painted Product Details
Product Image Size Selected: 15x7
Recommended Tire Size: 275/60-15
Price: $88.00 (each)
Estimated Availability:
In Stock
Shipping Cost/Delivery Date Qty:

ADD TO CART


SHIPPING
QUOTE

ADD TO
WISH LIST
VIEW ON VEHICLE

[The Champ]

Originally Posted by goatless

Nor was there ever a 1964 GTO that was designed to be run with 15" rims and radial tires. You know you're taking your life into your own hands every time you get in that death trap.

Ummm.....

Technology changes things every day. My front disc brakes must also make my car unsafe too.

If I were to put seat belts in my car, would that also make it a death trap?

Originally Posted by NotaT/A

Just for fun I checked with Discount and Tire Rack. Both suggest a 7" wheel with a 275/60-15.

Do either of Discout Tire or Tire Rack manufacture a 275/60/15 tire?

I didn't think so...

[goatless]

Ummmm... you miss my point, Mr. Champ. Both 15" wheels and radial tires were available in 1964 and yet the engineers at Pontiac said your GTO would be better suited to have 14" wheels with bias ply tires. They must have had a reason. You have decided to go against those engineers.

Maybe if I put it in your own words you'll understand.

"I think the point that many are missing here is that just because a 15" radial tire can physically be mounted to a 1964 GTO doesn't mean you should or that it's safe to do it.

Car manufacturers have engineers that believe that 14" bias ply tires is what should be used for this car model.

I'm sure that there are good reasons for their belief."

Really, I'm just messing with you. I understand that ideally a 275 would be mounted on a wider rim. We make judgement calls every day regarding our classics, modifying them in ways the original engineers never intended or even imagined. Sometimes it's ok to step outside of the "rules" as long as you understand what is at play. As you can see from others that have posted above mounting a 275/60 on a a rim that is .5" narrower than the recommended range has very little negative associated with it. The worst issue that I've seen are the guys that pop up to tell you you shouldn't do that.

[The Champ]

Originally Posted by goatless

Really, I'm just messing with you. I understand that ideally a 275 would be mounted on a wider rim. We make judgement calls every day regarding our classics, modifying them in ways the original engineers never intended or even imagined. Sometimes it's ok to step outside of the "rules" as long as you understand what is at play. As you can see from others that have posted above mounting a 275/60 on a a rim that is .5" narrower than the recommended range has very little negative associated with it. The worst issue that I've seen are the guys that pop up to tell you you shouldn't do that.

Yup we do make judgement calls every day.

But the original engineers on a 1964 GTO never knew or even dreamed about a 275/60/15 radial tire.

However the current engineers who make 275/60/15 tires have said that a 7.5 or 8" rim is the minimum width rim that should be used. I believe that these engineers have a clue about how the performance of that tire will be affected by the narrower rim.

I just think it's odd that when making a change to improve the performance of a car that one would knowingly do something that will most likely hamper the performance.

Do whatever floats your boat.

[Formulajones]

You guys crack me up. I don't think a 1/2" makes a damn bit of difference on a street car. You are talking a 1/4" per side. Even at 1" you are only talking a 1/2" per side.

I understand the whole "pulling the sidewalls in" idea, but a 1/2"??? Really? I wouldn't worry about it. Adjust the air pressures and forget about it. I've done this for many years and never experienced any ill affects, car drives fine, no center tread wear, and personally I like some sidewall on my cars anyway, gives me some curb rash protection

A track car is a different story. The "ONLY" time I really prefer a wider rim on my 275's are on my drag radial car, because in that instance, I lower air pressures at the track and want the most contact patch I can get for a small tire car making big power. There's a reason you see them mounted on a 10"+ rim in the 275 radial classes, although I don't care for the look, but you work within the rules of the class.

Hang on, I'll post a pic of my fathers car that will stir the pot some more

[Formulajones]

Here is a shot at the Pontiac Nationals,

That's a 295/65-15 drag radial on an 8" rim. Look up the recommended rim width on that and I'll guess it's 9" or more....

But, it works, and works good. 1.5 60 foot times and it hangs the front tires. He's used this setup for years.



Here it is at rest...



Personally I love the sidewall bulge look. I never jumped on the big wheel and rubber band tire bandwagon, I just can't stand the look of a wheel that looks as wide as the tire is. I've had no love for all this pro touring stuff.

[78w72]

didnt realize this would become a touchy subject, was just looking for some pics to see what they looked like on 7" rims. i realize most tire manufacturers "suggest" a 7.5 minimum rim, but that really is just a suggestion, nowhere does it say "if you mount 275's on a 7" rim you will crash & die" or "your tires will wear out in the middle after 100 miles"....

& tire rack, being a large tire & wheel company would NOT say a 275 is ok on a 7" rim if there was any sort of safety issue, especially in todays world of blaming & sueing anyone that is remotely related to an accident or issue. if there was any real safety issues with doing this, believe that tire rack would not say its ok. regardless of if they "manufacture a tire"

thanks for all the replies, i have considered all the points made. bottom line, for my street driven car, i feel the 275's on my 7.2" wide honeys they will be perfectly fine. will i do any autocross racing or drag racing on them? no. but i will roll around town at 55mph & less with no worries at all. & i agree with formula jones & others that 275's on less than 8" rims look just fine, actually pretty darn good. i do like the right 17" pro tour look on the right car too, but for the most part im old school.

this car will actually have 3 different tire/wheel combos. the 15" honeys with 255/60 front & 275/60 rear, 15x7 rally 2's with 225/70 tires, & a set of weld drag lites, 15x8 rear with 275/60 drag radials & 15x4.5 front skinnies with a thin radial for drag use & some occasional street use. & maybe a 4th option down the road of 17" honeys or other "pro tour" looking rim.

thanks again for the pics!

[Formulajones]

If you want a picture of an Fbody in a particular view, PM me your email and I'll pull my 70 formula outside for a couple of pics. I'm currently running 15x7 rallys on back with a 275-60, and 15x6 on the front with a 225-70

[The Champ]

Originally Posted by Formulajones

Here is a shot at the Pontiac Nationals,

That's a 295/65-15 drag radial on an 8" rim. Look up the recommended rim width on that and I'll guess it's 9" or more....

You'd be wrong...

With a 9" rim - you're right in the sweet spot!

Minimum is an 8" rim, max is 10"...

[Formulajones]

Originally Posted by The Champ

You'd be wrong...

With a 9" rim - you're right in the sweet spot!Minimum is an 8" rim, max is 10"...

Exactly my point

[The Champ]

Originally Posted by Formulajones

Exactly my point

Your point was that you were wrong about the minimum recommended width?

[NotaT/A]

So, I was beginning to get worried that God was going to kill a kitten every time someone hung a 275/60-15 on a 7" wide wheel. "How could it be," I wondered that the TRA and therefore most tire manufacturers recommend a 7.5 - 9.5 inch wheel for this application, but major tire companies will recommend a 7-inch wheel?

"There must be a logical explanation for this," I thought. I also have a lot riding on this, I have no less than 14 275 tires in my garage, and five of them are on 7" wheels. That's five kitten lives hanging in the balance. I'm more of a dog guy, but no one wants dead kittens on their conscience.

Anyway, I digress. I looked further into the 2014 TRA yearbook, and found relief. Yes, back in the supplemental section, page S-06 for those following along at home, there is an easily missed table labeled “Additional Approved Rim Profiles.” Luckily, there are three wheels listed in that table for the 275/60-15. They are 7J, 10J, and 11J.

What this means, is that even though it may not be recommended, it is permissible to use a 7, 10, or 11 inch wheel if you must/need/want to. I’m pretty sure this is how the tire stores can avoid litigation, and I can rest easy, knowing that the kittens are safe again.

[b-man]

Originally Posted by NotaT/A

I can rest easy, knowing that the kittens are safe again.