Different diameter vintage Schumacher 2" spike tires.

[tahustvedt]

I have one set of Schumacher front tires which are only marked "C.A.T.", which look like the stock tires for my Procat. I also have a set of tires which are marked with "C.A.T." and "Cut spike 3x20". These are larger in outside diameter than the other front tires. Both are 2" inside diameter. What gives? Was this done on purpose to achieve a front torque bias, perhaps?