Here's are some sketchs of the steering system for the 3012H, B10 early and 725/B1. There was a change in the steering between the early B10/725/B1 and the later tractors.
One change to note is the round gear verses the triangle shaped gear parts BJ in the 3012H sketch verses BF in the B10 early and 725/B1 sketches.
3112H (left) verses the B10 early (right) Steering Column:
B10 early front axles:
Simplicity 725 and the B1 front steering:
Steering comparison which shows the serial number change over (early verses late B10):
Tire sizes for various models
725, B1 and early B10 - thin front tires & thin back tires Big Ten - thin front tires & introduction of the regular back tires B12 - wide front tires & regular back tires B112, 3012 - wide front tires & regular back tires HB112 & 3112H - wide front tires & introduction of the wide back tires
Front Tires There were two sizes used for the front tires. Thin - Carlise 4.8/4-8 Wide - 16 x 6.50 x 8