Originally Posted by
ThermionicScott
It would be too embarrassing if they did. Earlier charts didn't allow for such wide tires, but after millions of mountain bikes were sold with 2" tires on 20mm rims, they caved and updated their charts to reflect the practice.
When MTBs first appeared on the market, they
did use wider rims...
Narrow rims just don't work well with wide tires. Technically you can do it, but you can't make it work right.
I've explained it elsewhere on the forum previously.
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My main beef with the ETRTO charts is that they claim that using tires outside of the stated rim/tire width combinations is "unsafe", and I cannot find
any explanation of that claim.
What I do know is that with motorcycles, cars, trucks, airplanes or anything else, you would NEVER mount a tire on a rim when the tire was
twice as wide as the rim; that is simply way too wide of a tire for the rim. Tires in general are
no more than about 20% wider than the rims they were intended for.