When you take a 4WD off the bitumen, the single most important factor is your tyre pressure. I've lost count of the number of people who we've come across that are bogged to the chassis rails with tyre pressures that are not correct for the terrain they are driving on. This is by far the number one reason people get stuck on all terrains, whether its soft beaches, mud runs or slippery rocks. It's not possible to pick the correct tyre pressure 100% of the time, but you can get very close, and adjust as you progress!
The biggest problem I see is people are not willing to let their tyres down enough. It's as if they are scared of breaking something, or rolling a tyre off the bead. Even heavy 4WD's that are around the 3 tonne mark can safely let their tyres down to 10 PSI for soft sand. It should come with the understanding that you don't accelerate, brake or turn sharply, but there's no reason for a tyre to come off the bead if you drive according to the conditions.
Below are 6 very important reasons for adjusting your tyre pressures when off road
Traction is something you can never have too much of. It refers to the ability of your tyres to grip on the ground, and create momentum. If the tyre spins without pushing the 4WD forward, you've lost traction. A loss of traction is almost always undesirable, and can easily result in you sliding backwards in an uncontrolled manner. When you are driving up something slippery, the correct tyre pressures give you the needed confidence that your 4WD tyres are going to grip and keep you going forwards!
Less track damage
Every time you spin your wheel off road, you are damaging the track. Obviously, some wheel spin is inevitable, but if the only way for you to get over an obstacle is for you to have all 4 tyres spinning at a million miles an hour, you need to re-think your strategy!
Less punctures and tyre wear
Australia is a big place. A really, really big place. A lot of the travel time in a 4WD is spent on gravel roads. If you don't run the correct tyre pressures, you will suffer punctures on a regular basis. This is cause for serious concern; if you use your spares up miles from help, what's the next move?
If you imagine a balloon that is pumped up to the maximum size, the second you touch it on a sharp rock it will go bang. Take another balloon though, and pump it up half way and do the same. The balloon with less pressure in it will usually mould over the rock, and not blow out.
4WD tracks will chew through your expensive tyres if you don't run the correct tyre pressures. Not only does a lower pressure make your ride more comfortable, the stress on your 4WD less but it saves you money in tyres too!
The biggest issue on sand is the lack of floatation. If you pump your tyres up to 50 PSI and try to drive along the beach, your 4WD will sink on 99% of Australia's beaches. Try it again though at 16 PSI, and you will have a pretty good chance. This is the tyre pressure I recommend for most 4WD's on sand. If its soft, don't be afraid to let the tyres down even more.
It's pretty simple; if your 4WD doesn't float, then it is going to sink, and your forward progress is going to die. If you feel your car sinking, let your tyres down a bit more! Another great way to increase your flotation is to fit bigger 4WD tyres. However, there are downsides to doing this, so do your research!
Less wear and damage to your 4WD
Some people argue that its a pain to get out and let your tyres down, especially as you have to pump them back up at the end of the 4WD track. However, they don't realise the extra stress they are putting on their 4WD by doing so. Every vibration and rattle is amplified, your chance of tyre damage is dramatically increased and the stress put on your car as a whole is increased. Instead of cruising down a soft beach at 15 PSI, you have to bounce it off the rev limiter with your tyres at 30 PSI.
When you run the correct tyre pressures for the terrain you are driving on, you will notice a huge improvement in the comfort inside your vehicle. Corrugations that are back breaking become much more mild, as do the knocks and bumps that 4WDing presents.
If you've been running tyre pressures that are too high, drop them a little and see the difference that it makes. You will be blown away! Essentially, the tyres act as a second set of springs; they take some of the 'punch' out of uncomfortable 4WDing!
So what's the right tyre pressures?
For your average 4WD's, below are the tyre pressures that are recommended for different terrains
Soft beach: 8 - 18 PSI
Normal beach: 16 - 20 PSI
Mud and rocks: 16 - 23 PSI
Gravel roads: 24 - 30 PSI
The above pressures are a guide, for when your tyres are warm. Make sure you consider the Difference in tyre pressures from hot to cold.
What do you usually let your tyres down to? Have you noticed a big improvement in letting your tyres down a few extra PSI? We'd love to hear from you!