If you’re trying to run a square set-up on your E46 M3 and want to use 275 mm wide tires, you are going to want to roll the rear fenders. The stock fender has a huge lip that’s about 10mm wide. Using this simple tool from Eastwood, you can safely roll the fender and gain back 5-7mm of that. The process is fairly straight-forward if you work one section at a time and keep the paint hot to avoid cracking.
Safely place the car on jack stands and remove the wheel. Bolt the tool to the hub and adjust it so the rolling wheel sits flat against the inside lip. Use the red lever to increase the pressure and slowly work the wheel back and forth on the fender lip, 6-8 inches at a time. Reheat the paint each time you pause to increase the pressure. I split the lip in thirds and worked each area before increasing the pressure. It took about 20 minutes to get the amount of clearance I needed.
I’m running a 9.5 inch wide wheel with an offset of 35. The tires are 265/35R18 Pilot Super Sports and I’m using a 10mm H&R Trak+ spacer in the rear so I’m thinking I can also run 275s without the spacers.