Thread: Letting tyres pressures down

Originally Posted by landy

Tombie,

To travel with under inflated tyres for excessive distance, at inappropriate speeds will as I'm sure you know will lead to over heating of the tyre. Particularly the sidewalls and (could) lead to an explosive deflation. My point, although I expressed it rather badly was that to not re inflate once the obstacle is traversed is a dangerous practice IMHO.

However, you do not know me, or have any knowledge of my skills, experience or aptitude. This of course does not excuse my 'irresponsible' comment and I apologise to rovercare for making it. I should have kept my mouth shut so to speak.

Regards

Nino.

My skin is thick, I don't mind being called four letter descriptive words if you like

The reality is, its a bit of a farce, tyre pressures. lots of people insist on running high pressure on terrible roads and ruin the ride, their vehicle and the tracks at the same time. the likely hood of a tyre exploding at 16psi is virtually nothing, simple fact is that it would have to generate enough heat to expand the tyre to a ridiculous pressure to explode, there simply is not enough air in a tyre at 16 psi to do that

A sidewall failure is another possibility, but again, more likely dues to puncture than from heat and even so, for those of us that have had tyres come to pieces at speed (thing retreads/bad tyre patches etc) its far from a disastrous occurrence, its merely noise a noticeable lean, bit of a wobble, which is controllable then come to a stop to see tyre with a flat section

So again, despite perception, its not an unsafe practice and in all honesty, I would say a roofrack that is loaded would make your vehicle more unsafe on the road than 16psi in your tyres

Landy,

Accept your statement. Thank you.

Once you start doing long offroad drives low pressure becomes preferable.

As Rovercare mentioned it's not a risk from heat, it's rolling off rims etc so slower speeds and/or care turning are necessary.

Sidewall damage, pinching between rim and surface are damage that the tyre is more susceptible to.

Driving appropriately for even several kilometres on bitumen before airing up is not a significant problem (obviously depends exactly how low you went).

It's all good...

No one who has done a lot of sand work, especially towing would suggest not airing down in beach cuttings and high tide driving. Of course you get most benefit and least likely pinching with a high profile tyre. I have never pinched a tyre at 16psi on beaches and cuttings. I air up as soon as I am back on bitumen for more than a couple of ks. At straddie for eg you come off Main Beach drive a few k slowly and get back on at Adder to run down to Flinders....I don't air back up for that but generally I go down to 22psi for most unladen running around the Island.

Cheers

Originally Posted by 303gunner

I think also that much of the Police training is to gain proficiency in a particular task or skill, not to develop expertise or master-level ability. The off-road course is to enable a trainee to proficiently operate a 4wd vehicle off-road, it does not turn out expert 4wders. Similarly, the rescue use of abseiling equipment does not create mountaineers or free-climbing rockclimbers. The firearms course demonstrates safe and effective use of firearms to trainees that may not have ever seen a firearm before, it does not create marksmen or competition-level shooters.


This is not criticism levelled at the various Police Services. It is equally apparent in many Industry training on a wide variety of skill subjects. It has long been said that there is no longer any such thing as common sense, as so many people from different walks of life have no life experience in many areas. Employers are now required to provide training for so many tasks and skills that in years gone by, the attitude would have been "You''ll be right, give it a go".


To advise "Operators" of 4wd vehicles not to air down would be a cautiously correct approach for drivers that are not enthusiasts or have a good understanding of the inherent risks and changes that result from that action. Any 4wd club training or commercial training outfit for recreational drivers would advise that is a beneficial technique, but would also go to lengths to explain the pros and cons and how it changes vehicle stability and dynamics, as well as risks to the tyres themselves. This technique would not be within the work requirements of the Emergency Services/Telstra/Electrical utilities/Rail Contractor to get out on site, so is not taught in the workplace.


But as to the other point raised, Is it LEGAL to drive with lower pressures, well that's a new one I haven't heard before.

A+.


I've spent 15 or my 28 years in remote locations, doing outback patrols etc and in desert or isolated non contact areas, I always ran a lower tyre pressure (even in split rims) and when I was headed towards the bitumin
(usually bitumin not near where I was living) then Id air up.... on a side note I always kept the front hubs locked in also until I was going for a drive for any distance on bitumin...

Ive never heard of this "illegal/legal tyre pressures... I would suggest that if you believe that you could justify it (and there is ample advice available that is able to point this one out) and you were
acting responsibly then I should think you'd be OK, even if it went to a court surely common sense should prevail (thats should..I promise nothing!!) Insurance companies have never requested a
tyre pressure from me after I have attended a prang... It is not recorded anywhere on a standard accident report..fatals or serious accidents thats a very different matter, everything is examined, filmed,
and very accurately recorded.

Ive unbogged more people with the "legal" tyre pressures that could have kept going with "illegal" tyre pressures than I care to recall.
Usually you pull up, say Gday, walk around dropping the pressures, and then drive it out... or guide them
"no, not in first, start in 2nd"
"how about moving that lever there...yeah now its in 4wd it may respond better"
"Its in 4wd but not responding?...MMM shall we spin these things in the middle of the front wheels? that may help...no free isnt for when you want to get free.... put it on lock"....

Some of the worst were during high summer... you see a pop top landcruiser trooper camper trundling towards the desert...yep almost a certain that its a 'FRITZ IN A BRITZ" there seems to be untold millions of german,
swiss, and similar nations peoples who plan to travel the desert in summer... ?? anyway, there is no instruction from the car company when they get the car, usually the manual has been removed from the glovebox, the map is an
A4 page showing ALL of Australia (that'll be accurate) there are no instructions about carrying water, about staying with the car if the strand , bog or get stuck etc.. no EPIRB etc....
They were often getting stuck and then wandering away from their vehicle believing theyd just walk and get help.... we lost a few due to this... Its not so much their fault as the rental companys irresponsible attitude...(in my opinion anyway)

One had the bloke stay with the car as the sheila he was with walked away... she died (on the track of exposure and dehydrations) he lived (although he was bad when we found him).
After he was flown out, I engaged 4wd, let tyre pressure down and drove out first try....

With a little guidance on collecting the car theyd let the tyre pressure down, engage gear and drive out themselves!.


anyway I have moved way off topic, (but you are spot on 303Gunner)

-sorry for the hijack!...

Originally Posted by Tombie

The individual you got your information from is wrong!

Under ADR 23 and 24 the recommended pressures are on the door sticker.
These are recommended for the vehicle load under normal use - Off-road is not considered normal use.

There are no laws regarding minimum pressures, there are laws on negligence.
Driving on a completely flat tyre at 110km/h leading to an accident obviously falls under these.

Instructors like the one you mention are frustrating, because they are spreading misinformation and scare mongering..

Essentially - he's full of it!

A local trainer / assessor and of SAPOL and other government departments just confirmed my suspicions...

It may have already been said, but here goes, a gazetted road is not classed as offroad as already mentioned by the Police Officer, regardless of whether the road is bitumen, sand or gravel.

Baz.

Originally Posted by Redback

It may have already been said, but here goes, a gazetted road is not classed as offroad as already mentioned by the FORMER Police Officer, regardless of whether the road is bitumen, sand or gravel.

Baz.

Gazetted roads are also not recognised as only sealed roads they can be any surface and condition.

Recommended is not "minimum" either.

Aren't vehicle tyre placards related to the original equipment tyres, which are almost always HTs, so that advice might not apply if an AT or MT was fitted, when the relevant advice would be from the tyre manufacturer?

Another interesting point is in relation to the increasing number of vehicles with 18s, 19s or even 20s and low profiles, including low profile ATs such as the Cooper Zeon LTZ, Pirelli Scorpion ATR and General Grabber AT. They still need to be lowered offroad, but lower them too far and they're likely to pinch. So how far should they be lowered? For example, if 26 was OK for a 16 inch AT, what would be right for a 19 inch AT in the same conditions?

Sent from my GT-P5210 using AULRO mobile app

Yeah, I'm guessing these guys didn't let their tyres down,
(at least they tarped up)