R20s..hmm well most of our middle east spec LC200s are R17 or currently R18s.We prefer R17s so as to add a bigger profile tire for our desert rides. the size I'm interested is 305/70-17 (coz its easily available and is 1/2$ than BFGs). When tested on stock alloys 17x8, they were, like you said, just an index finger away from UCA. this can be a potential hazard to UCA and obviously to the tire. Apart from UCA, i would have to trim the inner plastic guard to avoid excessive rubbing, while turning. The situation is much better if you have 17x7 steelies - So for my case, there are few solutions, as i understand it... to get alloys of different offset, like the TRD 17x8...continue search for hard to find BFG AT 285/75-17... or add a spacer in front (with TRDs) to move the 305s tire away from UCA ;p ...
But..i just love the looks of those beefy 305s !