Couldn't find much in the search on doing this.

I put some 12mm spacers on the mini (2005 with stock 16 rim & tire size).
I have a little rubbing on the driver's rear when having passengers.

Where exactly does the tire first rub the fender... I assume it's about where the side markers are. I don't see any wear on the sidewall, making me think it's hitting the tread area.

Anyone got some pics of what /where they trimmed?

 

You can get a tool that can do a slight reshape of the fender. It attaches to the hub and rolls over the tight areas and reshapes it slightly. Not sure who carries it currently but I borrow this from a friend who uses it on his lowered track car.

 

A fender roller. Had that done to my G35... but it was all metal. Surprised it would work on the plastic flare.

 

Take off the plastic fenders and roll the metal under it. You should only roll a little at a time and make sure the plastic fenders fit.