offset works with rim width, so you need to keep both in mind. you say 45 is good to have, but it won't work if the rim width is 8.5" or wider. 45 is the lowest you should go with 8" wide rims with 225 tires...if you got 8 with 235, you should consider going higher. however, 45 should be more than enough for a 7" or 7.5" wide rim using 225 (or narrower) tires. but pretty much, a 50 offset on widths from 7" to 8" using a 225 tire would be perfect!!!

like kleanaccord said, getting tires that will produce a rolling diameter as close to stock as possible.

seeing if the wheels come with an additional bolt pattern so it can fit more cars.

getting hubrings to fill in the gap between the whee's center bore and the car hubs...helps toensure the wheel spins round and provides more surface contacts.

getting lugs that fit the studs and sockets that fit the wheel openings.