yes the bolt pattern is 5x115, i dont know how to determine the offset... if there is a way to find out i will. i have seen these wheels on a regal, and they look awesome... it was black.
all i know about the offset is that i have centering rings that you can either have in or take out, i think that changes the offset...? so you would be able to choose what you want i assume...
the only reason im getting rid of these rims is because i upgraded from a gtp to a trans am ws6, and believe me i tried to figure out a way to get them on my TA. i wish i could hold on to them but i gotta upgrade my WS6 rims...
i paid well over 2 grand for this tire/wheel package new, so you are correct, it is a very good deal.