How Much Frame Notch to Fit 15x10’s?

[Chevyman540]

You really need to measure, the depth of the wheel well and the flange or face of axle to frame. When I did mine, I had 11.25" on one side,11.5" on the other, from wheel lip to the inside of the well. Also 5.5" from flange to frame. With that a rim with 5.5" bs would hit the stock frame. I run 295/55/15's on a 10" rim with 5.5" bs, I cut the frame back about 1.75". I have about 13" & 13.25" now from lip to inner well. I also made some new inner tubs.
Here's a pic of my notch.

https://imgur.com/DAku9oD

 

[Streetbu]

Quality control sucked on these cars. I could only notch my frame about an 1" on each side. Right to the seam. Once the body was back in the frame sits about 1/8" inside the wheel house. I can comfortably fit my 275/35/18's now might be able to sneak a 285 in there buts that's it for me...

 

[Local Hero]

I agree on the quality control with these cars. Terrible!

On my beater wagon, I run a 15X10 with 4.75 backspace and 275/60/15 tires. I run them because I had them laying around. I did trim and roll the outside lips and did a tiny bit of clearancing with a BFH to the inner wheel well.

On mock-up. everything seemed to clear. But during the first test drive the passenger side was rubbing really bad. So I notched that side. I never did anything with the driver's side. Only on super rare occasions, I'll get a slight rub on that side. It's only the raised white letters (tuned inside) making the contact. Hardly enough for me to justify the effort to notch that side.

The results were the same with two different rear axle assemblies. P.O. had a 3:73 in there and I swapped it for a 2:41 out of an 80 Cutlass. Both fit the same way. I often wondered if the frame was tweaked. But after reading posts on this site, I see that is pretty much par for the course.

When I bolt on the winter rims with the 235/75/15 snow tires on Pontiac Rallye wheels, the passenger side rubs the wheel well on big bumps. I'm about to purchase a new set of snows that are a little shorter anyway. We get A LOT of snow here.

 

[81cutlass]

This has me thinking, anyone run a 15x10 on a 81-87 grand prix with no notch?

I know GP's have the widest fenders of any G body. I fit a 295/50/16 drag radial on a 16x8 in my fender with a light fender roll, but want to go to a 275/60/15 on a 15x10.