First off, welcome to the forum.
The AWD and RWD wheels have different offsets. I think the AWD offset is around 44 whereas the RWD is 24.
Most 20" wheels come in 8" to 9"s wide, I would try to find 20x9's. As far as offset, I think a usable range would be from 35 to 50 but would suggest staying in the lower 40's. Maybe someone with more knowledge will chime in.
2011 Blackberry Pearl Charger R/T Plus
SpinTech mufflers & Aeroturbine resonators - Tinted (Panorama Hilite 40 & Huper Optik clear on windshield) - catch can - AEM Brute Force - Hotchkis springs - 180 tstat