I just put a new set on on my Ar3. Does anyone have any ideas about the kind of impact the 20's will have on my frame compared to the 23's I use on my SRAM 30 ALs? Any impute would be greatly appreciated.
Tyres should not impact the frame at all. Not a good idea.
If you mean how will they affect comfort then they will make the ride a little harsher. You will notice this a lot more than the frame.