Why big tyre used in rear of Tractors?

Answer: Tractors have big rear tires because, the larger the surface area of the tractor’s wheels touching the ground, the more pulling power you have. Like how tractor pullers have large tires.

Another reason is that the tractor doesn’t have to operate at a higher speed to get the same ground speed with larger tires. Gear ratios don’t have to be as high b/c of the larger tires.