BMW Repair: rear brakes, rear brakes, allen wrench

Question
I have a 1989 325i. While trying to replace the rear pads I discovered that I can't buy a wrench to fit the bolts holding the calipers on. What can I do to remove the old pads? I have a 6mm allen wrench and an 8mm wrench but the bolts appear to be 7mm or somewhere in between and the parts stores near me don't sell 7mm allen wrenches. Is this a apecial tool that only BMW makes?

Answer
I don't know that it's a special part but I'm sure if you called up a dealership or baverian autosport they would sell you one (at a premium price of corse).
your other option is to check the internet.
sears.com
snapon.com
ebay, I don't recall it being too extreamely obscure of a size so most tool supply places should have it.
-cheers