Wheel width (not diameter): what does it matter?

[Diesl Jp]

Ready to buy new wheels & tires and trying to educate myself on the impact of differing wheel width. And by "width" I mean the measurement from the inside edge to the outside edge. That is, if you're rolling it forward, the measurement from left side to right side. It seems that every search engine wants to translate that to meaning diameter, so I only get information on tall vs. short instead of wide vs. skinny.
And to be clear, I'm talking about the wheel and not the tire.

So what does it matter? Assuming the same size tire, what are the pros/cons of a wider wheel vs a skinnier wheel?

My specific scenario is that I've settled on 37" BFG KO2s (37x12.5 R17), and I intend to put them on 17" wheels. The rim width range for that tire is stated as 7.5-11.5.
I'm really liking the Black Rhino Chambers, and those have 8.5" width. So it's on the narrower side of the tire's range, but I don't know what impact that actually has. What difference in performance could I expect if I looked for a wider wheel? Fitment would obviously come into play, and I know that I'd have to be mindful of my desired backspacing if I went wider, but it's the difference in how the tire would ultimately perform that I'm ignorant on.

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[kevman65]

Since most of us don't run a high pressure in the tires, not a whole lot.

If you pressured the tire up to near maximum, your side walls would have a rounded appearance and the actual tread surface would crown, giving you a smaller contact patch and thus less than maximum traction. The closer to vertical of the side walls, the flatter and larger the contact patch.

8.5" wide wheel should be just fine.

 

[Blade1668]

Narrow vs wide rims in years past in some circles of off-roading people would run narrower than recommended rims to help hold tire on rim at lower pressure and to cut down on rim bead damage in rocks not many beadlock rims available or DOT approved. Go figure some of the "street" crowds ran wider than tire rims too. 10-12 wide rims with 8 in wide tires they had to run higher tire pressures too. ? might be the starting of the drifting and like stuff. ?
With the smaller tire sizes of years back you could "fairly" easily reseat tire bead on narrow rim if lost in first place. A ratchet strap or rope and tire iron with air compressor/tank. Not as likely running 40 and bigger tires now or as easy. I've "ran" 8in wide 15 in. rims with 12.5 wide tires for many years. (MT 33/12.5r15s or 35s on my XJ at about 20-25 psi. only times higher was if I was going to be on I-state and HWY for some distance. Nowadays a 35 or 37 inch tire is small. This might not help and just muddy up the water. Something else to think about is suspension flex, it started getting out of control in past (IMHO) about every Jeep club had a RTI ramp to see how far who could flex. If the tire on the ground doesn't have any contact pressure it's just a spinning tire the same as if it was in the air. What's new in off-roading today has quite likely to have been though the cycle and coming back around again.

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