Question for CAAD10 owners: How much clearance do you have above the rear tire at the brake caliper?

With 2011 SRAM Red brakes and 23mm Conti GP4000s tires I have about 2mm of clearance. Frame is 54cm. This struck me as a little odd so I thought I'd see if others have similar tight clearances at the rear brake. Plenty of clearance on the front. Pics of new bike tomorrow