My "new" '74 Duster- or why I need a project like a hole in the head

75slant6 said

245’s can be run pretty easily on the Duster’s. I’ve got 245/45/17s are on my Duster. I’ll have to measure to my wheel opening to compare to Brian’s Duster, but I’m running an HDK slammer suspension so I’m pretty sure it’s every bit as lower if not lower. I didn’t do anything to the fenders when I had it lowered on 1.03 torsion bars, but the HDK ended up dropping it at least another inch and the tire would rub the lip at full lock, so I ended up rolling the fender lips.
View attachment 1716077659

I guess here I had it at 23.5” but I think I raised it up some due to the tires hitting the bottom of the inner fender when I hit decent sized bumps.

View attachment 1716077658

Click to expand...

I am currently running a 245/45R17 on a 17x8 +30mm wheel. I guess I should just use that as my basis for if a 275/35R18 would fit if it was on a rim with the same offset.

Comparing my current tire to a Falken RT660 275/35R17 doesn't look positive. The RT660 section width is 1.6" wider, so .8" per side on a rim with the same offset as current. Tread with is a full 2" wider. That isn't going to happen without some sheetmetal mods. Even a Conti ExtremeContact Sport 02 is .65" wider per side in section width and tread width, which might work but will use up all of the available room.

Rule of thumb is the section width will change by 0.20" for every 1/2" of rim width, and since the measured rim for the RT660 is 9.5", it would narrow the tire and put it at more like .7" wider than my current tire per side on an 18x9 rim. Maybe? But probably not.

Wow, tire brand really does matter. The RT660 shows a section width of 11.2" and tread width of 10.1" while the Conti shows 10.9" and 9.4". Both for a 275/35R18. That's .7" more tread width for the RT660!