On my Cateye meter one can set the wheel circumference right down to the millimeter, so one is not limited to any table of standard tire sizes.
The fun thing is, the effective wheel radius will change with tire pressure and the load on the bike! The more the tire gets squished down, the smaller the effective radius!
I took my bike out on the road and rolled forward to bring the valve to the bottom. Then I marked the spot with a stone. I then coasted slowly and counted three rotations of the wheel, until the valve again reached the bottom of the wheel rotation. I marked this second spot with a stone. Then I measured the distance between the stones and divided by three.
Really there is a limit to the precision possible with such things! But it's fun to push toward the limit!