what size tyres can i put on a 2002 530i bmw it has at the moment 235 r55 /17 they look to small for the rims thank you

http://www.miata.net/garage/tirecalc.html

I used to put 225/55/16×7.5" at the front and 255/50/16×8.5" at the rear on my '01 540iT just so the the rear can better handle the torque of the bigger engine. I had also put 255/18×9" on all corners of my '01 M5 to dial out understeer. For 17 rims, the proper fitment is 235/45/8" front, and 255/40/17×8.5 rear. The best snow tire fitment is 225/55/16×7.5" all corners.

I have and continue to run 235/45/17 on my '01 E39 Sportwagen. I also have the Stock BBS Style 5's that are 9" wide. The stance is great and because I load the cargo bay down, I prefer the 94H durometer.