Tractor weight largely defines tractor capability in pulling applications.
Heavier tractors are built with thicker steel and thicker axles to withstand the stress of heavier loads.
Heavier tractors have larger diameter, greater breadth wheels/tires, creating a larger tire "patch" in contact with the soil. Rear tires are often ballasted internally with liquid, placing weight directly over the tire tread. Larger wheels and tires and a longer wheelbase permit heavier tractors to bridge holes, burrows, ruts and tree debris, increasing traction and reducing operator perturbation. Therefore, heavier tractors with large diameter wheels/tires have more tractive power pulling ground contact implements and tree trunks, pushing a loader bucket into dirt and pushing snow. Larger wheels and tires increase ground clearance, lengthening the period which row crops may be implement cultivated.
Heavier tractors have FEL lift and Three Point Hitch lift in proportion to weight.
When considering a tractor purchase, bare tractor weight first, tractor horsepower second, rear axle width/rear tire spread third, rear wheel
ballast fourth. Ample tractor horsepower is needed for PTO-powered implements such as Bush Hogs and snow blowers, but remains subsidiary to tractor weight in defining tractor capability.