A common question amongst the car community is ‘How much difference do 4×4 wheels make?’. This article will explain why there isn’t a simple answer and how it depends on who you ask.
To understand this fully, we need to first look at what makes tyres rotate. The tyre itself has many different forces acting on it, but for simplicity, lets just consider two;
Friction between the road and the sidewall of the tyre. Friction between the tread of the tyre and ground (this is caused by static friction instead of dynamic).
Sidewall friction acts as a retarding force, slowing the rotation of the tyre in a forward direction. In contrast, tread friction acts as an accelerating force, speeding up the tire’s rotation in a forward direction. By the laws of physics, these two forces must be equal in magnitude and opposite in order, so sidewall friction = -thread friction.
Static vs. Dynamic Friction
The tyre doesn’t move when static, so sidewall and tread torques exactly balance each other out. As soon as a forward force component is applied, static friction is overcome, allowing the wheel to rotate. For example, when moving from a stationary position or driving around a corner/bend, the wheels have an initial rotational momentum that reduces over time due to static friction being overcome by tread torque, causing rotation.
If we apply the same forward force again, it will cause twice as much rotation because now there isn’t any static friction resisting rotation. This is why driving around a corner faster will cause your car to drift. The speed of rotation increases, which reduces static friction, which means even less grip to stop it drifting further.
Traction vs Torque
This is where 4×4’s come in. The addition of extra wheels with their treads gives you more traction (grip) under acceleration, but the drawback is that more sidewall/static friction forces are being applied. Hence, you lose some grip under braking, but this isn’t as much as the increased acceleration grip due to having more treads on each tyre. So if you want maximum braking and acceleration, then 2x tyres would be best, or between 3-4x for balance. Visit us at https://www.autocraze.com.au/4×4-wheels/ to know more about our services.