AND, custom backspace wheels, and
most likely, the rear end will have to moved back, or the quarters trimmed, and
most likely, the quarter lips will have to be trimmed and/or rolled.
But,
a 345 is only a 345 on a wheel that is 70% of the branded size. so in the case of a 345, that will be 345/25.4 x70%= a 9.5" wheel .......
on a 12" wheel it will measure, I'm guessing, about 1.5" wider, so
(1.5 x 25.4 )+345= 383 which is 15.1 inches sidewall to sidewall; could be more I'm just guessing.
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But
It's a whole bunch cheaper, and not that hard to fit;
27.9 x 14s which could be 325/50-15s on 10s, or
26.6 x 13s which could be 295/50-15s on 10s
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I am a streeter.
I have fit the 325s into the stock tubs of my 68 Barracuda, which supposedly, are the same tubs as the Duster. The treads of either of these are inside the tubs. the 325's outer sidewalls come flush with the body, to a little outside and so, aggressive cornering with my lowered body, requires some forethought.
I narrowed my rearend to fit standard 4.5"bs wheels, and relocated the springs, and centered the rearend between the inner walls of the tubs; those 325s are pretty daymn close to rubbing even just at rest. AND, I had to pound a couple of intruding lumps out, that rubbed with changes in suspension movement. In a straight line, nothing rubs.
On the street, I run 24psi in the 295s for even treadwear across the face . This makes for interesting cornering as the body rolls over almost onto the sidewalls, and so, the backend does some steering of it's own. I got used to it, and I like it. At 24rear, 29front, the ride is pretty comfy.
Good luck with your project
