I am new to the wheel buying world and I have a few questions. I have an 07 Chevy "New Style" Silverado and I want to upgrade my wheels from those ugly steel wheels with the caps to some 20s. I am most likely buying used. I know the bolt pattern is 6 on 5.5 for my truck, does this mean I can get any 6 on 5.5 and they will work? I see all this stuff like offset and hubcentric, what does that mean? Also, my truck has TPMS (tire pressure monitoring system), do I have to buy wheels that are already set up for this? Last one, is it fairly safe to buy wheels from say craigslist or another private seller? Any other things I should know? Thanks for any and all help.