Tires, Tracks, and Wheels
Core concepts
Know tire construction (bias vs radial), ply rating, load index, speed rating, and tread patterns for agricultural use. Understand rolling circumference, inflation pressure effects on footprint and soil compaction, ballasting, and dual/triple configurations. Track content covers track tension, undercarriage wear, and track vs wheel tradeoffs. Wheel content covers rim types, lug torque, hub bearings, and offset.
Traps
Questions often assume higher pressure improves traction; overinflation reduces footprint and increases compaction. Another trap is mixing tire sizes across an axle, which changes rolling circumference and stresses the driveline. Do not assume ply rating equals load capacity without checking the load-inflation table. Track tension too tight accelerates wear.
Rule of thumb
Match inflation to load using the manufacturer's load-inflation table, not to the maximum on the sidewall. Keep matched rolling circumference across driven axles; a small mismatch creates wind-up. Check lug torque and re-torque after the first hours of operation.
Worked example
Replacing one rear tire on an MFWD tractor with a different brand of the same nominal size but different rolling circumference changes the front-to-rear lead. Measure rolling circumference (loaded radius) and replace in matched pairs or adjust to keep the specified lead; otherwise the driveline and tires wear prematurely.