Considering swapping the 12R/22.5 steer gear on my 1998 Peterbilt 378 to 315/80R22.5. Best as I can figure, I need to get a couple of 22.5 x 9" flat-face offset rims, mine happen to be stud-piloted Budds. With the present tires, I have a good 1"- 1 1/4" spacing from the inner sidewall to the steering box pitman arm at full right turn against the stops. Wondered if anyone had done this swap and wound up with clearance problems with the 315s. Tread width on 315s seems to vary from brand to brand, the ones I'm looking at are about an inch wider with a more square shoulder profile. My tire guy's opinion is that the flat face rims will offset the 315s outboard an inch or two which should more than compensate for the added tire width.
315's aren't much wider than a 12,so with off set rims you should be ok. my previous truck had 315 steers
I swapped my western star from 11r's to 315's. Got new rims, and its close to the steering arms, but clears. I think in the right combination of dropping a tire in a quarry road hole and turning, it might rub. I'll look and see if I have a part number on the rims I bought.
The tire shop I go to ordered what I need, they said it's a pretty common swap so they keep some mounted on hand, anyway. I'm actually happy with the 12R22.5s that are on there, but need the extra steer GAW that the 18 ply and extra width will afford. I field load a lot, and try to guess as close as possible, but you know how that goes, especially in mixed material. Since they went to the steer gear overload being a 'safety violation' instead of simply overweight a few years ago, can't be too careful. One of those is pretty much the same as a DUI on the license, here anyway.