Rim width...
A lot depends on your driving style, where you drive, how you drive, etc, etc
All tire specifications has a recommended rim width. From narrowest to widest and all of their published performance data based on them
Tires are the first defense before the shocks come into play. Tires have more than just weight carrying duties. Cornering, braking, steering, handling (curves, slalom, dampening, etc) and any combo or combo of them all at any given time
OEMs typically have the narrowest rim width for the tires they list on their vehicle specifications. Reason is that 'ride quality' is Paramount to their majority of customers
It has to do with sidewall static "bend back" and dynamic "roll over". Narrower rim per tire section width, will have more sidewall "roll over" and "bend back", so the tire takes the bumps by bending the sidewall even more during dynamic whatever's. Plus will have the highest slip angle, even when aired up to max sidewall listed PSI
Wider will have less "bend back" and "roll over". Plus will have a smaller slip angle and reduced 'ride quality'
Mine is 10" bead to bead on purpose. Want to reduce as much as possible: "side wall bend back", "roll over" and smallest slip angle. It does ride like a truck or track vehicle, but that is what I want and like. Ride quality is NOT on my 'Have to have list' and towards the bottom of my 'nice to have list'
All of this discussion goes toward re-engineering your suspension system...if you go out side of the OEM's recommended spec for wheels and tires, so read up on the HOW2's and effects there of...