73 duster 17" or 18" wheels ?

1972 Duster /Demon Stock front suspension

FRONT
(Mounting Surface to Fender Lip 4.75") Check Yours!
Wilwood Brakes will shorten this to 4.50"

*18x10 Rim w/ 25mm Offset
(.9” from fender lip) IDEAL
Will take a 255-265 Wide tire

**18x10 Rim w/ 35mm Offset
(1.275” from fender lip)
Will take a 255-285 Wide tire

***18x10 Rim w/ 12mm Offset
(.22” from fender lip) TOOCLOSE
Will take a 245/40/18 Wide tire TOO NARROW FOR WIDE RIM


REAR
(Mounting Surface to Fender Lip 5.5"(1.5” wide lip) ) Check Yours!
(Mounting Surface to Leaf Spring 5.875") Check Yours!
=11.375" space or ~10" widerim
3/16” or 4.76mm Offset to position rim to center

*19x11 Rim w/ 15mm Offset (Seems to be standard by a lot of manufacturers)
(Trim rear fender lips by ½”to ¾”) If they are 1 1/2" wide Fender Lips now!
.653 Rear Wheel Spacer on15mm OS Rims)
Or Trim Rear Lips to ½” wide andZERO offset on 11” wide rims

Or buy the MiniTub and Spring Relocation kit from US Car Tool To increase the 5 7/8" to 7 7/8" , then trim your rear fender lips to about 3/4" wide and you can fit a
335/30/18" Tire on a 18x12-45mm Offset Rim
or
305/30/18 on a 18x11-20mm Offset Rim

You can fit an 18x10 rim on the rear with a 285 width tire with almost no modifications.



Wow. Holy thread resurrection batman.



And, BTW, your numbers aren't right. First off, stock suspension for a '72 Duster/Demon would include SBP brakes, and you won't find any of the rim dimensions you listed for SBP. If you did, your offset numbers don't match the narrower track width. As for the wilwood brakes, they have several options and not all of them result in the same offset.

You will not fit a 285 on a 10" wide rim up front without significant fender modifications. Not happening. I run 275/35/18's on 18x9" rims with a 27mm offset, and I am at the limit at both the fender and the frame. I've already re-worked the lower front fender corners and braces, and used all of the adjustment in the fender mounting to get enough clearance. Tomswheels ran a 285 on an 18x10 on the front of his Valiant, but he also pushed the front fender out with a hydraulic jack. 25mm to 35mm is the offset needed for 9" to 10" wide rims, depending on your brake package and car. 35mm will usually require some kind of increased offset with brakes and possibly a spacer. That's using 73+ disk brakes as the reference point for the offset.

In the back you won't get away with an 11" wide rim without cutting stuff unless your car rides as high as a 4x4. Remember, rims are measured on the inside lip where the tire bead mounts. An advertised 11" wide rim actually measures 12" on the outside edges. The rear quarter lip can only be trimmed back about a 1/2" before you get into the spot welds holding the quarter to the wheel tub. Cut any more than that on most cars and you'll have to reweld the tubs to the quarters. I cut mine back a 1/2" and still lost a few spot welds in the process.

+15 is about where you need to be in the back with an A-body 8 3/4 with BBP axles. Since you're talking about 0 offset, I'm going to assume you don't have an 8 3/4 (7.25" and 8.25" rears are about 1" narrower than the 8 3/4).

A 285 might be possible on a stock car, but only one that ended up with generous clearances or that doesn't sit at a lower ride height. On my Duster I was maxed out with a 275 when I had the stock spring locations and uncut quarter lips.

Currently I have 295/35/18's on 18x10's on my Duster. That required a 1/2" spring hanger/shackle offset (42" c-c on the spring perches) as well as a 1/2" trim on the quarter lips, and I'm still maxed out for clearance at my ride height.