Quick question for wheel and tire gurus…

[7T Swinger]

I have 12” from fender lip to frame on rear of my car. Non-Mopar ( 1963 Pontiac Grand Prix ).

Wanting to run 275/60R15 rear tires which are 10.8” wide.

This would only give me ~5/8” clearance on either side of the tire..

Is this enough clearance or am I asking for trouble?

Thanks for your time.

Much appreciated.

 

[64mopar]

It is getting close,but should be okay,make sure there are no suspension components to interfere as well.
As long as the rear end has little to no side movement and you do not plan any serious road racing.

 

[dano]

Probably going to depend on the suspension firmness and set up. What consists of you suspension? Does this have a solid rear axle?

 

[69FBCuda]

10.826 is the tread width, the rim width will determine the "bulge" easily 1/2"-3/4" on either side at the top of the tire. If you really want to cut it that close I would have the tire mounted on the rim and measure again. You also need to consider rim backspace/offset or the "tire assembly" will not be centered in the wheel well.

 

[12many]

I have 12” from fender lip to frame on rear of my car. Non-Mopar ( 1963 Pontiac Grand Prix ).

Wanting to run 275/60R15 rear tires which are 10.8” wide.

This would only give me ~5/8” clearance on either side of the tire..

Is this enough clearance or am I asking for trouble?

Thanks for your time.

Much appreciated.

Remove both wheels, lay a straight edge on the drum faces so the straight edge goes up into the wheel well. Measure front and back spacing. Check at various points of the wheel well lip. Then you’ll know exactly what you have for room

 

[Oldmanmopar]

unless you have aluminum control arm bushings there will be some side movement. A pan hard bar would be suggested with clearances that close. GTO/Tempest, Chevelles, Skylark and Cutlass bodies all have the same control arm suspension which is not that stable with side movement unless serious mods are done.

 

[7T Swinger]

Thanks to all for the replies.

I think 255/60R15 is the max I should go here instead. This wld give me ~1”clearance on both sides of the tire.

Much appreciated.

 

[33IMP]

The first thing you need to know is the backspace available on the wheels you want to use. More bs is better. If you have too much bs, it can be fixed with a select fit spacer, too little and the tire crashes into the fender.
I have several sets of wheels/tires that weren't necessarily bought for the car they are on, using spacers I have made or bought solved fitment problems.

 

[64mopar]

I believe the 10.8 will be cross section of the tire measured on a specific width rim.
Wheel width and back spacing will be important to the final outcome.
The 275's should not be too big if all is right.

 

[7T Swinger]

I’m waiting to hear what my tire shop says about suggested wheel width, backspacing, etc. I have triple-checked these dimensions:

Fender lip to frame: 12”
Wheel mating surface to fender lip: 5-1/8”
Wheel mating surface to frame: 6-7/8”
Pilot bore: 3”
Bolt circle: 5 on 5”

 

[7T Swinger]

I know you guys like photos like I do, so, here you go…

 

[33IMP]

I'll ask again. What wheels do you want to run, what width, and what BACKSPACE is available? THAT will determine how much tire you can run.
BTW, love the Grand Prix!

 

[7T Swinger]

@33IMP

“I’m waiting to hear what my tire shop says about suggested wheel width, backspacing, etc. I have triple-checked these dimensions”

 

[33IMP]

@33IMP

“I’m waiting to hear what my tire shop says about suggested wheel width, backspacing, etc. I have triple-checked these dimensions”

I get that, but help us out. What kind of wheels are you trying to put on it?
Torque thrusts? Slots? Magnums? Salt flats? Centerlines? Keystone? Weld wheels?
You can have ideal dimensions, and maximum tire width for the space available, but if the wheels you want don't match the ideal, then you will have to find out how much compromise is in order......
15x8 torque thrust one piece is probably around $150. A CUSTOM bs two piece 15x8 torque thrust is about $600.

 

[7T Swinger]

I’m leaning towards something like this..