With radial tires, I don’t think you can go too wide as long as the wheel is narrower than the tire due to the fact the the steel belted radial tread composition won’t let it “cave in”.Funny I was thinking about this during my drive back from the PNW and talking with Corey Young a little about it. (just realized he bumped the thread :homer: )
The last post makes sense to me, once the sidewalls are about vertical the tread is going to want to cave in, at least on a bias, a radial may not care since the sidewalls flex so well.
I definitely think you can go too wide, not only will the tread want to cave in, but I would think you will loose sidehill stability.
I feel like 3-4" less than tread width is probably good, depending on height. The 54s and 49s I've seen on 14s seemed perfect. But honestly, even the 49s and 47 pit bulls I've seen on H1's seemed to work OK. Even a 12" on a 14" tire might be a bit much. Especially since you are going to have a lot of sidewall. I would love to see someone compare different width wheels on the same tire.
With that said, I have 36x14.5r15 radial STS on 15x7 steel wheels, no beadlocks just duct tape. My buddy has the exact same tires on 15x10 method beadlocks (15x11). His tires are considerably wider and the tread is “flatter” where mine are maybe .5” taller but the tread has some “rounding” to it due to the narrow wheels. I do think his work better than mine, but his are on a RZR and mine in a cj5 :grinpimp: