I got this off a BMW site:
It may help.
Well today GIO_21 and I were bored, so we adjusted my coilovers and washed the cars, then sat and did nothing... after realizing that both of our cars had rubbing problems in the rear, we decided to roll our fenders, hehe.
Step 1: Remove the filling under the fender
Our cars have this rubberish filling between the fender and lip preventing the fender from being rolled competely. You have to remove as much of it as you can in order to begin rolling. We used a small flathead and an hours worth of elbow grease to get it most of it out. My car was a pain in the ass since I had so much of the filling, and it was so hard to come out. GIO's car had less filling and it came out with the touch of a finger, lucky bastard, lol. Well anyways, just get as much out as possible so that you can feel the sharp edge of the fender. You have to jack up your car and put it on a jackstand to work at it, unless you want to just remove your wheel.
Step 2: Find an old baseball bat and some fat friends
Luckily Gio plays baseball, so he had a ton of bats, we just grabbed an old beat up one.
Jack the car up and place the bat between the tire and fender, then lower the jack completely so that the bat is now stuck between the tire and fender. Make sure you place the bat at either the front or rear of the rear fender.
Open your trunk and get a few of your bigger buddies to sit on the trunk ledge so that the car sinks and puts even more pressure on the bat between the tire and fender.
Step 3: Roll it!
Find a trustworthy friend and have him hold the bat and press down on it, getting it as vertical as possible. Turn on your car and keep the door or window open so you can communicate with your trusty friend. If you placed the bat at the front of the fender, but your car in reverse and slowly roll it backwards while your trusty friend pressed the bat and moves with it as it rolls along the fender backwards. Do the same if you placed the bat at the rear of the fender, except with the car in 1st gear or Drive if you have a step.
Repeat this about 3 or 4 times. Jack up your car and remove the bat. Your fender should now be rolled!
Some people may consider this way cheap and stupid, but it definatley worked for us, and it saved us the time and money of getting it done at a shop. Our fenders did not have any paint crack or anything, and there was no visible difference outside. However, the metal under the fender is now rolled upwards noticeably, and we both no longer have rubbing problems
__________________