Correct Tyre Pressure??

Sparta,

As a rough guide I drop about 25% off my highway pressures when I hit the dirt roads, similar to what you will find on your trip to the Ridge and Birdsville. I then drop by about 25% of highway pressure again when I get on the sand.

So I start on the highway at about 40psi, drop to about 30psi on good dirt and about 20psi in the sand.

Don't take this as being prescriptive it is just a guide and you should find what works for you. The roads you are travelling could all be done reasonably safely at highway pressures and sensible speeds.

Duncs

38-40 on bitumen.....
12-20 on sand depending on boggyness.....

The birdsville and Strez Tracks are normally pretty good cond but they are notorious for Gibber patches which is what cuts tyres at highish speeds with too much pressure (eg high 30's).... Not slowing down for the dips will result in cut tyres also... Pressures on these roads should be lowered to high 20's....

G'day have a look at PostID: 26409 I hope that clarifies things for you :-)

As a rough starting guide I agree with Duncs & Voxon's preasures although I must add when you drop your tyres down you should also drop your speed. Continuing on at the maximum speed limit on the Birdsville track fully loaded with 30 psi would give poor road holding & can lead to overheating & tyre failure. Additionally no concideration has been given to the total weight of the car & trailer. One preasure will not suit all cars, tyre size & make. A heavily loaded 100 series IMHO should have higher preasures than a Hilux for example or a 7.50 x 16 skinny tyre should be inflated more than a 35x12.5 fatty.
I run about 36 psi in my 105 series which is slightly overloaded (4 girls) & often travel up to 100 kph on a road like the Birdsville track. Have had very few puntures out central OZ except for picking up nails & staking cross country.
Don't be afraid to experiment a little with your preasures to see what handles the best for your rig.
Cheers Craig............
HZJ105
285/75 MTRs

G Day Mate !
I have a 2003 Navara 3.0 Lt TD,, and fitted Cooper AtR's and am not long got back from a Simpson Desert Crossing, from Birdsville to Dalhousie and Big Red taught me very quickly about tyre pressures
Ran 24-26 psi up both the Birdsville, and the Oodanadatta tracks, and a bare 18 psi in the Simpson,, and did it all too easy
On the Black stuff I run 32 in the front,( warm tested ) and 30 in the back, and rotate them every 5000 km.
Never look like having a problem,, but then again I am 1000 kg lighter than you ,, so I suggest that you should start to look at 5 psi more that my figures and adjust to suit
An old mate of mine once explained to me that you should look at the curve effect across the thread, to guage the correct air pressures. Just slightly is a good starting point ...
Well I've been doing it for 30 years now and I am still no expert , so I guess it comes down to the combination of the Manufacturers recomendations and my mates theory ,,
Cheers Mate
Bucky