Just wanted to give folks a heads-up on the 700x37c Conti Contact (2011) tires. They measure just over 34mm when mounted on a 24mm (outside) rim. This was after 24 hours at max psi. By contrast, my 700x32 Vittoria Hypers were only 1mm narrower, and actually taller than the Contacts.

I think it would be helpful if we could compile a list of actual widths for the popular commuting tires. Once I replace the batteries in my calipers I'll post some exact measurements.