Bicycle Mechanics - Centering brake calipers

I recently installed a set of SRAM Rival brake calipers on my bike. All went well but unlike Force, Rival doesn't have the screw on the side to make side to side adjustments. So it is critical that centering be done via the brakes' mounting post. But that requires a 12mm wrench. As far as I can tell, Park, Pedro's nor Ice Toolz do not make 12mm wrenches and my craftman wrench is too wide. Is this a problem for any other Rival owners? I have a 13mm, should I just use that?

So, no leads as to where to find a 12mm hub wrench?

So you need a really thin wrench for the locknut on in front of the fork? Something like these perhaps:

http://www.google.com/search?hl=en&biw=1780&bih=994&tbm=shop&q=Super+Thin+Wrench+12mm&aq=f&aqi=&aql=&oq=

If you can't find a wrench, you should be able to get them centered without it. I've never used a wrench to center any of the old side pulls I work with that don't have centering adjustments. The key is to get the bolt behind the fork (or seat stay bridge) almost tight. Then jam the caliper askew. If you do this in the right direction the caliper should center itself as you tighten the bolt fully. It may take a few tries to get it right.

^
Yeah, I kinda did that.

Thanks guys.

You could always buy a cheap 12 mm wrench and grind it down until it fits.