Involved in the legal field for 20 years . . and "You are safe with staying within the industry norm. . but not being lesser than . . "
A low-rider sedan using 13" skinny rims meant for a tiny car, and crashes, has rock hard hydraulics for his show frenzy, ----> is in jeopardy in any lawsuit. I've seen this.
A gent putting on a (bike) tire that is well within an industry norm in size , is safe. For instance : a 150/70/18 tire is : 3.50" --> 4:25" in most industry standard charts. JUST an example, and a guy can put on what he likes, but he's in safe territory 100% of the time. What will get you in trouble is installing
underrated tires, then something bad happens. It's especially bad if forensic investigation indicates the owner used the tire under inflated or over-loaded. A variation of that gets trickier when a gent installs a considered "non industry standard" tire, ie: dirt bike knobby tread on a street bike, then injures somebody. Now it's a good court battle, especially if the only roads available are soft dirt roads. Note: the guy may have put a 130/xx/18 knobby on.. . . well within a fitment range.
Take note: RE uses a tubeless tire type rim at the inner shoulder, that's impressive. Not the spoke/nipple ports, just the shoulder. That makes a tubeless tire, with a tube, have a really nice anchor at a puncture moment. A standard old-school tubed rim, w/o that shoulder, can unseat itself instantly at speed. That sucks. I've had that too many times since 1970. When I replaced my
OEM tire, that bugger came off the rim STAT scary easy, by pushing my palm on it. Daaaaamn. !!
Just putting on a tubeless tire, with a proper tube, VERY snug fitting on that shoulder, later requiring a serious levering to remove, is very very very nice. Take NOTE: That will be a non-OEM tire replacement that is an upgrade , in any circumstance. Just stay within industry fitment norms.