7.25 drum to drum measurement

Tuesday said
Thank you, again. I have called my shop, and booked her in, as they are specialists in chassis dynamics and will measure everything, including space to the quarters and advise on tyre widths and we can address the axel width. I think this is too important for me to make a guesstimate - especially if we widen the axel.

@72bluNblu - out of interest, what are your preferred wheel and tyre specs (if you're not using stock wheels). I have a 450+hp 360 Magnum going in, set-up for daily driving but with more power low down - dynamically, on the street, the aim is punching in and out of corners and some autocross down the line, once a Tremec goes in - any of your excellent advice always appreciated.

I run 18x9's and 18x10's with 275/35/18's and 295/40/18's on my Duster. But making that work and taking advantage of the Falken Azeni's with a 200 tread wear takes more than just the right wheel specs. Obviously it takes that too, but literally the only stock suspension parts I run are the spindles.

It sounds like you're building a "pro touring" style car, and depending on what other suspension work you wanted to do you could run 18x9's with 275/35/18's all the way around if you did a 1/2" offset on the rear springs. Which would be pretty simple if you're already having a rear axle built.

michiganpat said
my 1976 small bolt pattern 7.25" measured 57 1/8" drum face to drum face. they want that measurement since that's where the wheels mount and determines axle shaft length and where the wheel sits in the wheelwell. housing flange to housing flange doesn't mean much without knowing what brakes you're using (1.5" wide drums, 2" wide drums, 2.5" wide drums, discs off of a jeep patriot, etc). I was actually quite suprised when I measured my duster that with the stock width, even though it has that hippo on stilts look with the 215/70R14 tires on small bolt pattern ralleys (which measure .5" positive offset, or 3.75" backspace for 5.5" wide wheels), the tires were about perfectly centered in the wheelwell, 2" spacing to the inner wheelwell and 2" spacing to the lip of the wheelwell opening.

so what width you want to do will determine what offset wheels you plan to use and how big of a tire you want to go. 0 offset rims and maximizing tire size, I'd want the width probably 56" or so. +30mm offset (late 90's bullit rims), you'd probably want something more like 58.5" wide....

I'm guessing you measured that on the car with a tape measure? If anything they'd be the same or narrower than the BBP 7.25's, which themselves are narrower than the SBP 8 3/4. I haven't personally measured one of the '73+ SBP 7.25's, only the BBP version, but based on working with other members here on their backspacing all of the 7.25's are narrower than the 8 3/4's. The backspace that works on an 8 3/4 puts the tires right on the springs with a 7.25 of either bolt pattern variety.