1970 dart max wheel size

toolmanmike said
Yes. How much and what difference do the big bolt axles make?

doug 371 said
The distance from the bearing to the flange is greater on big brake axles...think it's about 3/8" per side...

5/16” is the number, that’s the change in the flange stand off going SBP to BBP. So, add a 1/4” to 1/2” to the backspace. The offset to center the wheels with the BBP axles is about +13, the factory 15x7’s with a 4.25” backspace are +6.

toolmanmike said
So a little more backspace for the same wheel width. My 7's and 255's are very close to the fender lip on the drivers side and probably only 1/2" clearance on the spring side. Now, 255's on 7" wheels do have a bit of sidewall bulge. May be a narrower tire would give a little more clearance. Let's put it this way, I don't have any need to try a 8" wide just to say I can. I wouldn't want to trim or roll the lip to make it happen.

Yup, that’s a good point. 255/60/15’s are measured on a 7.5” rim, so putting them on a 7” will squeeze them a little and putting them on an 8” might stretch them a little compared to the published specs. It’s a small difference either way, but 255’s are a tight fit.

For the BBP axles you’d want a 15x7” with at least 4.5” backspace.

toolmanmike said
Looks like you have a Duster/Demon. Those wheel houses are different than Darts.

Yes they are!!! By about a full 1”.

275’s will fit a Duster/Demon/Dart Sport with no cutting at all with the right backspace. Can’t do that with a Dart unless you install a 1/2” offset on the springs.