Wide rims, narrow tires, and tread width

[Ronsonic]

Originally Posted by Andy sti

It's all about the dish, tuck and stretch!

Hella Flush!

[dddd]

Surely the tread gets pulled toward the inside of a corner, helping to keep the thicker crown of the tread in contact with the road.

I am able to test tires at extremes of lean locally, as there is an extended climb within blocks of my house where the tall curbs are canted asphalt that can be ridden on.
I very often go to these hilly neighborhoods to scuff in the tires on used-bike purchases. Initially, the tires slide to the bottom of the curbs, but after holding on tight for a couple of hundred feet the clean rubber is exposed and the grip becomes reliable. I have used the combination of wider rims with tires as narrow as 20mm for training rides since the late 1990's, which always worked well enough if the tire didn't use a touring grade of rubber.
From looking at the tread of the tires I have experimented with, it appears that I never approached the edge of the tread cap. The unused rubber "chicken strips" were pronounced and of good width.
Where the combination of narrow tires on wide rims might be an issue was pointed out earlier by HTupolev, as a very rough surface or bits of gravel/rock can reach up quite a bit higher than the median road surface itself and possibly cut the sidewall.