Question

Explain why a tractors big tyres stop it sinking too far into the soil

Answer 1

Pressure (on the soil) is reduced by spreading it out over a greater area using much wider tires. The formula for pressure is F/A or force divided by area, so the more area there is to spread around the force, the less pressure the tire will have to sink itself into the soil

Answer 2

Tractors with big tyres have larger contact area on ground. Since the area is large, the pressure acting becomes small and it can roll on ground easily with out the danger of sinking in ground.