<span class="highlight">Tyre</span> <span class="highlight">Pressures</span>

Depends on vehicle weight and type of tyre, myself in a 2005 100 series TD on 35x12.5 18 Procomp Tri wall muds loaded for outback touring.
Rough dirt roads 22 front 26 rear
Sandy roads start at 18 front 24 rear and have been as low as 12 all round.

This is what I do.....Hope it helps

TYRE PRESSURES.



THE 4 PSI RULE.



Check your tyres prior to going on a trip.

Let's say ALL tyres read 36 psi and call that START PRESSURE.

Drive for an hour then stop and check the tyre pressures.

If your psi is 40 then you are spot on with your starting pressure.



If your psi is MORE than 4psi above start pressure, then that start pressure was too LOW.

ADD PRESSURE NOW.



If your psi is LESS than 4psi above start pressure, then that start pressure was too HIGH.

DROP 2 PSI NOW



FOOT PRINT RULE.



Sitting on a straight hard level surface measure the LENGTH of the rubber making road contact.

That is called the tyre "foot print".



Bitumen 180mm.



Gravel 220 to 240mm.



Sand 300 to 350.



OH HELL!! 400mm.

With an F250 with quite a heavy load, and a Bushtracker caravan loaded for several months of travel, we went to 25 psi cold all round for roads such as the Gibb River. We ran 27 on the Tanami, and i think 25 would have given a better ride. Again 25 all round on sandy roads. Ran about 30 when road was constantly changing between dirt and bitumen. Only went below 25 on the F250 at Carawine Gorge :O (and used our Max Trax); we got out OK leaving the caravan at 25.

Motherhen

hi wilco, this is my take on tyre pressure, started many years ago with fj55, then a 60 series, then a 80 series, now a turbo diesal 100. I see a dirt track i run 40 psi. plus. never let my tyres down. after many thousands of ks i have destroyed 1 tyre only. chunk of grader blade. natturaly if i am in the dunes or on the beach i dump my tyre pressure but never on dirt tracks eg, birdsville, strezleki, bore track etc.. many years ago in broken hill i was getting a tyre fixed and said to the old fella at beaurepaires whats the best thing to do out here and he said " pump the bloody things up mate,not down". took his advise and it works for me. Blew a side wall out of my caravan tyre just out of alice a few years ago, getting a new tyre in alice the bloke said what pressure yu runnin, i told him 35 psi. he said yep thatl do it pump them up. my views only, cheers mm

wilco

18-22 on rough dirt roads, depending just how rough

12 front 15 rear in sand

Naturally reduce speed accordingly

Cheers
Bucky

Depends also if you are using tubed or tubeless tyres...

Remember with split rims you need higher pressure...
Because the pressure is measured from a more confined area with tubes...

Sand/Sandy roads i have 20 front and 30 rear....( example waa line ).......
Rough dirt roads i have 25 front and 35 rear.... (example mount dare to dalhousie ).......

Normal driving on road 60 front and 70 rear..... (example melb to adelaide )


There is some good info below in the replies about tubeless tyres......

I went out to Steep Point (WA)last week and ran 32 psi on the corrugated section and about 20 on the really soft sand section.
Did it easy,smooth ride and no wheel spin.
Landcruiser weighed about 2700kg

Hello Wilco,
I used to use 38psi in the front tyres of my Hilux DC and 45 psi in the rears on rough dirt roads when carrying a heavy load. However, following a trip to Cape York and plenty of travel over rough roads in Central Australia - in the company of folk who rarely adjust their tyre pressures - I was alarmed at the level of damage to the tyres. Punctures weren't a problem, however fractures to the tread and torn lugs were.

I now run around 34 and 38 psi respectively on rough road and I've noticed a marked decrease in tyre damage, as well as a much softer ride. Ín essence, I let as much air out of the tyres as is needed to have the them just begin to bag.

On two crossings of the Simpson Desert I ran with 20 and 22 psi and significantly less when ascending Big Red.

I, too, have received mixed advice from tyre dealers. So, I just use a commonsense personal formula: less pressure = lesser load and lower speed = less shaking = less worry = less damage.

Hope this helps,
Cheers,
Netnut

There are only so many things that stuff a tyre. One is punctures the other is tyre failure usually because of heat build up. The lower the tyre pressure the more heat build up. The more flex because of rocks etc the more heat build up. My view is that the pressure is a trade off between the two ie failure and punctures. Yes you can decrease tyre pressure but you must reduce speed as well. If you pump the tyres up too high there is little flex and you can get punctures that you may not have got with the lower pressure. The conditions change the equation too. If you are in the Flinders there is a lot of sharp slate and the locals run there pressures at around 35 with an empty vehicle. I don't advocate pick a pressure by the way, this is just an example.

To tell you the truth I would rather have a puncture than any sort of tyre failure at speed. So I usually stick to manufactures recommendations as much as possible.

Yes you can play with the pressure but you need to know what the flip side is. I have tried all the options in the past and the 4/6psi rule is probably the most sensible. Saying x psi is not useful, the optimal pressure varies by vehicle, tyre and load. The 4psi rule takes this into account.

Basically to avoid punctures/tyre failure the best solution is to drive slower.

Sand is a totally different beast and you are usually driving slowly so let them down enough to get where you are going. I'm talking soft sand here not just a sand based track.

Steve

On 'blacktop' 4.5 bar
Gravel roads 3.0 bar
Soft Sand 1.5 bar

This is one of those debatable issues...debatable because there are a lot of variables that can apply to the individual circumstance..eg. Tyre age and type, gross weight on board and the nature and composition of the dirt road etc.

Normally I am accustomed to letting tyres down to 25-28 on the rougher dirt roads but if I have a heavy load on board I would probably increase to 32-34? at the back to compensate. Don't want them to bag too much. Some brands of tyres bag out more at the same pressure than others. The ground in the Flinders has a high percentage of sharp shale and any open pattern tyres (such as running muddies) are more susceptible to shale punctures between the tread and also side wall.

I let my tyres down on dirt roads simply because that's what a Tyre man in the bush told me early on in my 4WD career and what most of my 4WD mates do. Is it correct...well most of the opinion is probably for it while a few are against it. A mate of mine never lets his down...runs at 40 all the way (except soft sand of course). I would say he has had more punctures than me but then he tends to run his tread lower than me before replacement and buys a cheaper brand of tyre.