15x8 Grand National wheel question!

[hndzoff]

I'm thinking of getting my rear stockers widened to 15x8's. They will have a 4 inch back space. What size drag radial will fit and look good. I don't want to do any modifications like boxing or rolling the lip's. I did a search and didn't really find anything specific.

Thanks, MIke

 

[toofastforyou]

Mike, I've had some 15"x8" GN wheels made a long time ago (see the first two pictures). In order to eliminate the need for wheel spacers, you need a rear spacing of no more that 3.5" ! More rear spacing than that will result in tire rubbing issues against the frame for sure. I mounted some Good Year Eagles P275-60-15 on them but just for a comparison, I have some racing slicks (bottom left picture) size 10"5x28.5" also monuted on 8" wide wheels with a rear spacing of 3.5" and it's the biggest tire I can stuff into the stock wheel opening without doing any frame notching. The only thing I did was to roll the fender lip, that's all. The last picture (smaller) shows the car's stance on the street...:wink:

Hope this helps...

Claude

 

[hndzoff]

Claude, Thanks for the quick reply. What size drag radial would you suggest for a stock size 15X7 wheel that that would look good?

Thanks, Mike

 

[SouthernCal GN]

I ran mine with 275/60R15 M/T drag radial- awesome fit, and great hook.

The stock rims- use a 235/60R15 or 255/60 drag radial. You could squeeze a 275/60 on them, but you risk accelerated center wear due to crowning.

 

[toofastforyou]

"hndzoff", I agree with "SouthernCal GN" about using a 7" wide wheel which limits you to a 235-60-R15 tire...Anything bigger than that might look nice, but probably won't give you an advantage traction-wise because the tire will have a tendency to ride in the center wearing that portion of the tire much faster than the rest of the tread, because of the rim being too narrow...In my opinion, if you want to go to a bigger tire like a 275-60-15, you should get at least a 8" wide wheel or even better a 10" wide wheel.

Claude :smile:

 

[gpadilla1071]

I'm looking for rims too and I read that 15X10 will be good for a 275 tire. So my question is... Will the rim stick out? or will be just right? I'm having a hard making a decision as to what size of rim I want for the rear...

 

[SouthernCal GN]

I'm looking for rims too and I read that 15X10 will be good for a 275 tire. So my question is... Will the rim stick out? or will be just right? I'm having a hard making a decision as to what size of rim I want for the rear...

15x8 is the best size IMO- you can use the 275/60 15 (28" tall) or the 275/50 15 (26" tall) without drama. The 275/60 fills the wheelwell very nicely, and hooks great.

For a street car, I feel the 15x10 is too wide. On my car, 15x8 GN rims with 275/60 15 drag radials gave me over 8k of service on a daily driver.

 

[hndzoff]

15x8 is the best size IMO- you can use the 275/60 15 (28" tall) or the 275/50 15 (26" tall) without drama. The 275/60 fills the wheelwell very nicely, and hooks great.

For a street car, I feel the 15x10 is too wide. On my car, 15x8 GN rims with 275/60 15 drag radials gave me over 8k of service on a daily driver.

SouthernCal GN, What is your backspace on the 15x8's. Do you have any rubbing issues? Are you using spacer's? Do you have any pics of the wheels on your car?

Thanks, Mike

 

[Roger]

I run 15x9 84 & 85 GN wheels, which I had widened. I'm not sure of the back spacing, but I believe they are 3 3/4". The 84 & 85 clear my Baer brakes without the spacer I had to use on the 87 Ttype wheels.

 

[toofastforyou]

"gpadilla1071", I wouldn't be afraid of using 15"x10"s...I'm saying this because I now have some 16"x10" wheels with 275-55-R16 tires on my car with a rear spacing of 4.25"...so I guess that a 15"x10" wheel could use the same rear spacing too...The rim is flush with the outer fender lip...(see picture below)...Also, if you ever decide to go to even wider tires in the future, you'll be ok with 10" wide wheels... If I knew this back when I had my 15"x8" wheels made, I would've had them made 10" wide instead... :frown:

Claude :smile:

 

[SouthernCal GN]

SouthernCal GN, What is your backspace on the 15x8's. Do you have any rubbing issues? Are you using spacer's? Do you have any pics of the wheels on your car?

Thanks, Mike

Hi, Mike,

No rub issues. I think the backspacing is 4" (but I can't be too sure). No spacers.

Pics emailed to you.

Pete

 

[hndzoff]

Hi, Mike,

No rub issues. I think the backspacing is 4" (but I can't be too sure). No spacers.

Pics emailed to you.

Pete

Pete,
Thanks for the pics's. Looks nice!!

Mike

 

[Grumpy]

I believe 4" is the magic backspace on a 8" rim :biggrin: 31/2 is out near the wheel well ...unless ya roll it or jack up the rear of the car

 

[turbofish38]

I believe 4" is the magic backspace on a 8" rim :biggrin: 31/2 is out near the wheel well ...unless ya roll it or jack up the rear of the car

+2. I agree. I ran 15X8 with 4"BS for many years. Either 275 tire will fit with out any issues or drama. I ran the 15X8 Corvette steel rallys with a 9.0/10.0X26 slick at the track. Right now I run those same 15X8 GNs on the front with a 225/50 tire. No rubbing at all and the suspension is also lowered. Turns like a slot car with the smaller low profile tire too.