Here is what I based my "will it fit" discussion on...I am told these measurements are based on a 15x10 rim. I think these came from another member on this board.
Tire 315/60R15
Section Width: 12.40 in
Overall Diameter: 29.88 in
Sidewall Height: 7.44 in
Radius: 14.94 in
Circumference: 93.87
I am happy to double check the actual measurements on my set up for you in the morning.