If I have a 40 series tire, will it offer the same protection regardless of what size the rim is?

For instance, let's say I had a 40 series tire on a 20 inch rim.....would a 40 series tire on a 22 inch rim theoretically provide the same protection against potholes? Or would a 40 series tire actually offer less protection on a 22 inch rim because the wheel itself is bigger diameter wise?

I just bought a Cayenne as a second car....and would love to put new wheels on. However, the roads suck here. The proper size for a 22 inch wheel is normally a 35 series tire....and I've bent a lot of rims before (albeit on cars) with that low of a profile.

20 inch wheels' proper profile on the Cayenne is a 40 series tire...which I think would be OK. However, I have heard some people running 40 series tires on 22s.....but I don't know that it would offer the same protection as on a car with 20 inch wheels. As a point of reference...I know Escalades with stock 22s have like 55 series tires....great protection against bending rims.

21s won't work because there are hardly any tire choices (meaning the tires are twice as much as 22s).

 

http://www.discounttire.com/dtcs/infoTireMath.dos

the second number is the aspect ratio which is a % of the width of the tire. So 35 on 275 is thicker than 35 on a 245 etc