Wheels for a duster offset and backspace
Sorry I'm late, looks like the big wheel haters are already trying to force their archaic nonsense on somebody else because they still haven't figured out how lousy their BFG T/A's really are.
What size tires are you looking to run? A '74 Duster can actually run a ton of tire with the upgrade to 17" rims. Up to 255/40/17 in the front, and as much as 275/40 or 275/45/17 out back if you want. 255's out back would be pretty easy, the 275's will be tight and might take a little work on the quarter lip depending on body tolerances.
Not sure what your exact plans are for the car, but it based on the set up you've shared so far, it sounds like you're setting it up for better handling. If that's the case, you have a lot of options if you go to a 17" rim. In the back the 8.25" axle is narrower than an A body 8 3/4, so be careful who you listen to for backspace. What works on a BBP or even SBP 8 3/4 will be different for an 8.25", even with the Jeep disks in the rear adding a little to the track width. Are you still running factory disks in the front?
In the front, you have a ton of options. Your limiting factors will be the fenders on the outside, and the outer tie rod on the inside because of the 17" rim diameter. That limits backspace to about 5.6" on most rim designs. Assuming you're using the factory BBP, 73+ disks you can use any of the following-
17x7 with anywhere from 4.25" to 5.6" of backspace, or +8 to +38mm of offset (so those Motegi's will fit on the front). Tire is limited to a 225/45/17 or a 225/50/17, the first will be kinda short (25"), the second a little tall (25.9")
17x7.5, 4.75" to 5.6" of backspace (+10 to +35 for offset), with a 235/45/17. Or, you can run a 245/45/17 on that rim also, but you'll want minimum 5" of backspace for that (+18 offset)
17x8, 5" to 5.6" backspace (+12 to +30) with a 245/45/17. You can also get a 255/45/17 on that rim, it will be tall at 26.1", but should work if you stick to 5.25" to 5.6" of backspace (+20 to +30 offset)
In the back the 8.25 is the same width at a BBP 7.25. I was able to get a set of 275/40/17's on mine with a 17x9" rim and about 4.75" of backspace, but it was super tight on the springs in the factory location. You'd have a little more room though, because those disks widen the track width some (about 5/16" per side). Those Motogi's won't fit at all, too much offset. So...
17x8 with 4.25 to 4.5" of backspace (-6 to 0 offset), 245/45/17's would fit pretty easy. 255/45/17's would fit too.
17x9", 4.5 to 4.75" backspace (-12 to -6 offset), 255/45/17's. That rim is a better fit for the 255's, less sidewall squeeze. You may need a small wheel spacer on the inside, but with the disks maybe not.
17x9, 4.75" of backspace (-6 offset), 275/40/17's. This is a tight fit, so tailoring with a spacer or trimming/rolling the quarter lip may be needed depending on your ride height. They'll fit, but I wouldn't suggest it unless you're willing to do some trimming, especially since you're sitting fairly low with Hotchkis springs in the back.
You'll notice the offsets/backspacing is very different from the front. The track width front to rear is very different with BBP disks up front and an 8.25" out back, it will make wheel choices more limited.
I like 15” wheels, too, but I think 17” and 18” give a more purposeful look to the car, 18” wheels are the only way to get some real rubber under the car without fender flairs, and they don’t make modern tires in anything smaller than 17”. Not everybody wants modern radials (i.e. designed before EFI was a thought) but if you do and you want a 275 or so tire on the front in a stock fender, 18” wheels are pretty much your only option. And I am excluding drag radials from the definition of modern only because they really aren’t intended to do more than go in a straight line.
There is a huge thread on here about running 17” wheels, might give a search for that.
Based on the OP’s mod’s, sounds like he is looking for something better than 1980’s hockey pucks.
Best I remember, a 17” wheel is about maxed out at right around 5.5” of backspacing as a general rule. The issue is usually the tie rod end rubbing on the wheel, and sometimes the upper balljoint. Most are going to 18” wheels to avoid that interference, at which time you can run more like 6” of backspacing and a 9” or 10” wheel without hitting anything.
There are better people than myself to help, that is just what I remember. Look up 72bluNblu, he runs a 285 tire on the front of his car.
Got me while I was still typing my response!
Everything for 17's is above, 18's are definitely easier up front because of the tie rod deal. I run 275/35/18's up front on 18x9's, 285's would take 18x10's and some more push on my front fender for sure. 275 up front is the limit with
relatively stock bodywork :D
