Tread pattern of a tyre is what majorly determines its off-road ability.
There are numerous ways to increase traction; in this blog we’ll concentrate on tyres. One of the first modifications that people usually get done once they buy their 4×4 is to change its tyres. Tyres not only drastically alter the off-road capability of your vehicle, they also completely change the looks of it as well.
An easy and surefire way to increase traction is to lower the pressure in your tyres. This will lead to a broader contact patch between the tyre and the ground. It also lets your tyre conform to the shape of any rock or surface, thereby aiding traction. And lastly, a wider footprint lets you float over muddy and sandy obstacles. The only drawback is that lowering the pressure reduces your car’s ground clearance. You shouldn’t lower the pressure too much, else you run the risk of unseating the bead. Usually 18-20psi is safe for most tyres. It is extremely important to inflate back the tyres as soon as you hit the road. Driving at high speeds on under-inflated tyres will lead to a blowout.
How do you choose the right tyres?
Tyres are usually chosen by their tread pattern. Although there are many different patterns, let’s break it down to three major types: Highway Terrain (HT), All Terrain (AT) and Mud Terrain (MT) tyres.
Stock off-road vehicles are generally supplied with road-going tyres, also called Highway Terrain tyres. These perform well on the road, giving you good tarmac grip, fuel efficiency and less road noise. However, they perform horribly off the road. As soon as the tyre’s narrow tread void gets filled with muck, they act as slicks and cannot grip the surface adequately for traction.
If you are going to use your vehicle primarily on the road with little off-road usage on tamer trails, you should consider switching to an all-terrain tyre pattern. The tread voids in an AT remain close (though larger than the HT tyre), which allows them to roll smoother, quieter and often last longer. The tighter voids prevent them from excelling in mud though.
If you are going to use your vehicle primarily off the road, then you should choose from a multitude of Mud Terrain tyres available. The greater the tread spacing, the better they throw out mud and dirt. The larger spacing, however, results in poor road handling and excessive road noise.
A simple way to choose your tyre could depend on your primary usage. Use the formula shown above (see box).
The next thing you need to decide is the tyre size. Huge monstrous tyres look very cool on the vehicle but they do have their drawbacks. Although larger diameter tyres are the only way to increase the ground clearance of the vehicle, they result in a speedo error, and may foul with the fenders during maximum articulation and this will mean further modifications to prevent damage. Larger-diameter tyres will also affect your crawl ratio and the gearing in the differential will need to be changed to compensate for that.
A simple formula to determine the correct crawl ratio is to multiply the current differential ratio with the new tyre diameter (in inches) and divide this by the original tyre diameter (in inches), and you’ll arrive at the required differential ratio.
Monstrous tyres affect the steering components and unduly stress the drivetrain as well. Large, heavy tyres can eat away into your suspension and most manufacturers may not honour any warranty claims resulting from a tyre swap.
After selecting the tyre you want, you need to decide whether you want to change the rims or not. If you are not upgrading tyre size, you can stick to the original rims. But upgrading to wider tyres may necessitate your changing the rims to make full use of the extra width. Here, you have two choices – either you can go in for metal rims, which are extremely robust but heavy, or you can opt for alloy wheels, which are light and compensate for the added tyre weight and look good. However, they may crack if they take a direct hit from a rock and unlike a metal rim cannot be hammered back into shape.
What’s the bottom line? Tyres are the one modification that will give you quick and instant improvement on the off-road capability of your vehicle. Tyres are expensive and choosing the correct tyres is extremely important. If you are unsure about which tyre to select, do not be afraid to ask an expert who will advise you keeping in mind what best suits your needs.
Also See:
Tyre care: How to avoid and repair a puncture
Tyre care: How to select the right tyre for your car, SUV
