All About Tyre Pressures

IMG_5032When you head off road, there are many things you need to think about and prepare for, but the most important thing is tyre pressures.  Whether you are out for a day on the beach, a play in the bush or dealing with mud holes or corrugated roads, ensuring you have the correct tyre pressure for your situation can mean a happier, safer and easier drive for you.

So many times we have seen others in situations that could have been avoided had they let their tyre pressures down.  It is very important to have a little know-how in this area, but do remember that you need to know what works for your vehicle.  Vehicle type, weight, tyre size and terrain will all have an effect on what tyre pressure to run.  You want to give your vehicle every chance to perform the best it can and correct tyre pressures can certainly help with this.

Factors to keep in mind when dealing with tyre pressures?

  • HeatRemember that as you drive, your tyres heat up and this in turn will increaseIMG_5752 the tyre pressure, so always keep this in mind. You may start your day at 40psi on the road, but after a while the pressure can increase to say 43psi.  In the same respect, you may have been driving and then reduced your pressures to drive on the sand to 18psi.  When you get up the next morning, your tyres are cold and you may find that the pressures are now actually a lot lower.
  • How long have you been driving for remember that tyres heat up as you are driving, and therefore, the pressure inside will go up, so always take this into account when adjusting tyre pressures.
  • Speed Generally, the quicker you drive, the hotter the air in your tyres will get, and thus the higher the pressure will go.
  • TerrainIf you are driving on rocky or corrugated roads your tyres will be flexing more than normal and this will also have an impact on them heating up quicker.
  • Weight – How heavy is your vehicle and how much extra weight have you added for this trip?  Adding more weight should be a factor in adjusting tyre pressures, but also remember that more weight will mean higher temperatures and therefore higher pressures occurring as you drive.

Why do you need to adjust tyre pressures when off road?

IMG_2031Traction is very important when driving! Losing traction (or grip) when off-road can result in sliding and losing control of your vehicle, which can be very dangerous.

Punctures are not something you want to encounter when you are driving off road. We always carry spares with us, but obviously hope we will never need to use them!  By running the correct tyre pressures for the circumstances you can lower the risk of punctures and also prolong the life of your tyres.

Floatation is important, particularly for sand driving. When driving on sand, your 4WD will want to sink and dig in to the sand, so you need to lower your tyre pressures significantly to ensure that you can ‘float’ along the top of the sand, rather than digging in and trying to push through it.  You will definitely notice the difference and it’s so much easier on your vehicle as well. This is also noticeable in mud as well and helps to preserve tracks.

Track damage is never a good thing. We all want to keep our tracks open for everyone to use and enjoy and one way to do this is by using correct tyre pressures.  If your wheels are constantly spinning because you don’t have traction, this in turn can damage the track.IMG_1957

Comfort for yourself and your passengers can be greatly improved by having correct tyre pressures. Driving on a gravel or corrugated road with road tyre pressures will result in you feeling every bump and rattle, but by reducing the pressures slightly you’ll be surprised at how much more comfortable the ride is.

How does it actually work?

When you reduce the pressures in your tyres you effectively increase the ‘foot print’ of your 4WD.  Remember that your vehicle is connected to the road purely by the four tyres, so it makes sense when you think that if you decrease the pressure, the tyre balloons out and you now have a larger area in contact with the ground …. A larger ‘foot print’.  This helps to spread the weight of your vehicle over a larger area and in turn, helps to stop it digging or sinking into the ground. The more tyre in contact with the ground surface, the more traction you should have.

IMG_3717If you think of your tyres as a balloon, you blow it up completely and put a pin to it, it will pop immediately.  If though, you only blow it up half way and do the same, it will probably take more to pop it.  This is what happens off road, if you are driving on rocky/gravel surfaces and you let a little air out of your tyres the tyre itself tends to mould or shape itself over the rock and takes a lot more to ‘pop’.

What is the right tyre pressure to run?

Well, that’s a hard one as all 4WD’s are different and many factors come into play.  It depends on your vehicle, how much weight you have on board, what size tyres you have, where you are going and what you are doing!  Personally we believe the following is a good guideline to follow.  Works for us, but may not necessarily work for everyone!

  • Road: We run our tyres at 38 psi, but you should use the tyre placard in your car as a guide for you.  Keep in mind that this will change when you have different sized tyres to standard, extra weight or load etc.
  • Beach (sand):  18 psi (you can go lower if the sand is very soft, we generally won’t go lower than 12 psi)
  • Mud:   18 psi
  • Rocks:  18 psi
  • Gravel:  28 psi  (again, depends on how rough the road is)

The above are an average of what we find works for us.  Depending on the surface we may need to go a little lower from time to time.  You will learn to read your vehicle and what works best forIMG_5044 you.  As an example, while driving on roads up around Cape York, we found that they were much more corrugated than a normal gravel road, so we found that we had the smoothest ride by running 22 psi on the front and 24 psi on the back.

Always remember

  • When your pressures are low, never brake, accelerate or turn sharply.
  • Always remember this saying, “low equals slow” ….. Meaning that the lower your tyres go down, the slower you need to drive.
  • Once you leave the track or beach always re-inflate your tyres to ‘road’ pressures as soon as you can.  Driving on the road for prolonged periods, or at high speeds, on underinflated tyres can be damaging for your tyres and can be very dangerous as well.
  • Therefore, when lowering your tyre pressures, always keep in mind that they need to be inflated again. Is there a service station close by once you leave the track? Do you have a compressor onboard?

So next time you are driving off-road, keep all of this in mind.  Knowing and having the correct tyre pressures for the terrain you are driving in is probably better than any other mod you can get, it will always get you further when driving off road, and it’s free! Not only will your passengers be more comfortable and happy, you will be safer, you will be helping to prolong the life of your vehicle and tyres and most importantly you will be protecting the tracks as well.

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One thought on “All About Tyre Pressures

  1. Pingback: All About Tyre Pressures | Rifleman III Journal

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