Why tractors have bigger rear wheels?

You might have wondered about giant rear wheels of a tractor. They look huge and create a sense of curiosity in our mind. But have you ever thought about the reason or the science behind it. Lets list out the physics and engineering behind it. There are several reasons for using bigger rear wheels :

- Bigger rear wheels mean more contact on the surface with the ground which provides a lot of contact area for force transfer. Hence the pressure on the ground is reduced and vehicle can easily move on wet and swampy farm land. 

Tractor traversing rough terrain

- If we put bigger wheels in front they will hinder the the drivers view. Smaller wheels in the front mean better view forward.

Also Read : Tubeless tyres

- Smaller wheels are less heavier and hence can be steered easily. Heavier wheels require more steering effort by the driver and may cause fatigue to him.

-Small size wheels have small turning radius, hence vehicle can be turned easily .If the turning radius is large the vehicle can not take sharp turns.

-The tractors need to traverse very rough and uneven terrain so they need very high traction and torque which are provided by large wheels. Large wheels have large contact area with ground which increases tractive force . Large wheels also provide very high torque at contact surface which helps it to traverse any difficult and uneven tracksvery easily.