It might seem to some drivers that all tires are just tires, but there are many different types, even for the same vehicle and wheel size. There are also several main differences between regular tires and 4×4 tires. There are also different types of 4×4 tires.
What most people call 4×4 tires are actually 4×4 off-road tires. But there’s also 4×4 all-terrain and 4×4 on-road tires.
First, we’ll cover off-road tires and look at the differences between them and regular tires.
Off-road 4×4 tires
Off-road 4×4 tires are designed to retain grip on mud, dirt, grass and snow. If you look at them, you’ll notice that the tread on these tires is deep, with larger gaps in-between the tread pattern. This allows the tires to retain friction with the ground in these adverse conditions.
With a road tire on a muddy surface, its shallow tread would quickly become clogged with mud, leading to a loss of friction. Friction is crucial for grip. Without friction with the road surface/ground, the tire would simply spin. On muddy terrain, as the tire spins it will dig the vehicle’s wheel into a hole; meaning that the task becomes even harder.
On an off-road tire; the much deeper tread-depth is much harder to clog-up. And even when these gaps in the tread pattern are full of dirt and mud; there’s enough rubber in contact with the ground to retain enough friction to move the vehicle. In fact, with off-road tires in general; much more rubber is in contact with the ground at all times than with a regular tire.
What are the cons of off-road 4×4 tires?
Of course, with more rubber in contact with the ground and much more friction being created this also has two major flaws:
1) When on a normal road surface they will become worn much faster than a tire designed for road use. Off-road tires driving on a normal road surface are creating much more friction than is actually needed to propel the vehicle forwards.
2) They actually create so much friction that it slows the vehicle down considerably, leading to excess fuel consumption as well. The greater the friction between the vehicle and the road; the harder the engine will need to work to move the vehicle at the same speed.
Despite what manufacturers of off-road 4×4 tires may promise; these are the trade-offs of using off-road tires. They are not as good as road tires on a normal tarmac surface. No matter how good the tires are; the laws of physics still apply. But they are far superior to road tires on the correct surface.
If you’ve ever witnessed a vehicle driving on a normal road surface with off-road tires you will notice a loud, persistent whining. This is the sound of the rubber in contact with the road, and what you’re actually hearing is the rubber being worn away by the road surface. Yet on the correct surface they are silent. In general, when tires are doing the job they’re designed to do; they will not wear as quickly as during incorrect use.
What makes 4×4 tires different from normal tires?
Next we’ll talk about the difference between 4×4 tires and normal tires in general.
The drive train on a 4×4 vehicle is different to that of a normal vehicle. The power comes from the engine, through the gearbox and into a transfer box. From here it travels down a prop-shaft to a differential unit. Commonly referred to as a “diff”. From this differential unit; the power is then distributed to the wheels via drive-shafts. There are two differential units on a 4×4, a front and rear diff.
Essentially this means that all wheels are working rather than having two passive wheels. They are all sharing the task of moving the vehicle. This is why it’s harder to get stuck when going off-road in a 4×4 vehicle as opposed to a front or rear-wheel drive vehicle. They are sharing the load in a way that many vehicles do not, so it’s a good idea to fit tires recommended for use on your vehicle. Fitting tires meant for a 2-wheel drive car can cause problems with wearing and grip.
Fitting the exact tire recommended by your manufacturer is good practice anyway and it’s a good habit to get into. People often like to modify their vehicle to make it their own; but they don’t have the benefit of the insight that has come with spending millions of dollars on testing. Rarely is it the case that fitting the incorrect tires to the car will actually improve the performance. It’s more likely that they will become worn.
4×4 All-terrain tires
Now let’s talk some more about the main different types of 4×4 tires we’ve yet to mention.
These are designed for both on-road and off-road use. While they may not be as good as either on-road or off-road tires at their specific task; they are a more ideal balance between the two. They will not really excel at either task, but they can be driven off-road reasonably well and they can be driven on-road without the excessive wear and fuel consumption of off-road tires. But they will become worn more quickly than on-road tires.
4×4 On-road tires
These are road tires specifically designed for 4×4 use. In the case of a larger 4×4 such as; a Landrover Discovery; they will typically feature slightly larger tread-depths than on a front-wheel or rear-wheel drive car, because the manufacturers presume that the vehicle will be used off-road at some point. On these large 4x4s the standard on-road tires are more typically what we refer to as all-terrain tires on other vehicles.
On a 4×4 saloon or hatchback car, the on-road tires will look much the same as on any other car, though they may have tread patterns more suitable for the occasional off-road use. They will also often be a uniform size, whereas 2-wheel drive wheels can sometimes differ in size between front and rear wheels.
So there we have it. The main difference between 4×4 tires and regular tires is that a 4×4 is usually designed to go off-road, and the tires (even the standard type) are as well. Off-road 4×4 tires are totally unsuitable for on-road use. If you live in a rural area that requires off-road tires, but you also do a lot of driving on tarmac; it would be a good idea to invest in all-terrain tires instead. It’s a rare occurrence that you may require the extra capability that off-road tires will offer over that of all-terrain tires. So, it may make more sense to go for all-terrain tires except in the very worst conditions.
ABOUT THE AUTHOR
Sophie Smith is a trainee engineer from Brisbane, Australia.