What size wheel can I put on a BMW 530i ?

Im looking for a custom wheel for my wifes 2004 BMW 530i. What size wheel can I put on it and what size tire, 19's or 20's? I would like to fill the wheel well without changing anything around. What about offset? I don't want the wheel to far in the fender, or sticking out. Any suggestion on brand? I don't want to spend more for the wheels than I did for the car. Also, who's got the best deals?What size wheel can I put on a BMW 530i ?go to www.bavauto.com - they have some pretty neat wheels, and they won't change anything about your car. If you buy huge wheels, you're going to get inaccurate speedometer readings, and your car won't perform as well. Also, big wheels could end up lifting your vehicle (larger diameter without lowering suspension), which would look terrible on a 5 series. Your factory wheels are 17" in diameter. Changing the diameter 3 inches would effect your speedometer, because the formula the car uses to find the speed would be thrown off (it's electronic, not mechanically through the transmission like it was on the ooooold bmw's. If you really want some new wheels, just get some new 17's. Maybe 18's. But there's really no reason to go any bigger, or you'll start rubbing up against your fenders when you turn.