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.
3012H Steering:
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):
Tires
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