Tyres up or down?

Hi Stephen

Is this the one you were talking about?

Adam Plate's Pink Roadhouse Tyre Pressure Guide

NB This link is to the Pink website and is the work of Adam Plate

Cheers

Anthony

Hi Anthony

Yes, that's the one I was talking about. It was good sound advise that followed correctly, will save you a lot of trouble.



Cheers



Stephen

Your false teeth don' t rattle and you don't shake the bejeezes out of your vehicle

Hi,

Ive done all those plus many other restricted areas around Alice Springs in all directions for almost 2 years while working out there. Done the Ghan, Chambers Pillar, Finke, Mereenie, Plenty highway, Birdsville, Strezlecki, Cape York all on BFG muddies at 40 PSI. Had OME suspension which took care of the corrugations, so I guess i owe it all to the tyres being good quality. Got great wear from them too so I still cant justify dropping pressures.

Cheers

I second what Off-Track has said. I do the same. Personal choice in the end but never had a problem with hard tyres on gravel. I do drop them on sand and sandy tracks - easier on the car and easier on the track.

Serendipity

Exactly!
Most times I was well loaded too. Using tyres as shockies has to stress them more.

Cheers

you guys say that, but i've travelled thousands of klms also up to Cape York, across The Simpson Desert, down the Ghan Line, up through the Gulf over corrogations and sharp rocks at decent speed and also whilst towing a camper trailer, etc etc and never blown a tyre. the only time i have gotten a couple of flats when was i was running tyres that were barely street legal, and they were being run at normal pressures.
if it's a decent gravel road i don't deflate my tyres, but once the corrogations or sharp rocks start, it's deflate time in my book.

I'm with Off -Track on this as well.

Run BFG AT at 40psi (actually at times 50 on the rear of the Landcruiser because of its load)......bitumen /gravel/rocks all the same and never drop pressures unless on sand when it needs the extra footprint and to reduce stress on the vehicle.

Yes I have travelled some pretty serious outback tracks in the NT and Pilbara / Kimberley. Side wall exposure and increased tyre temperature of the tyres when lowering on rocks/gravel I believe is too serious to risk.

As for tyre damage....not yet..apart from damage when off road making my own tracks...and thats nothing to do with pressure and all to do with scrub bashing.

I am far from an expert on this but have read a heap on dropping pressures and I can say I am now a real fan of this. I picked up the same leaflet at Pink Roadhouse last year and it made perfect sense.

If you follow a vehicle over a rocky track (using that as an example) just watch a tyre with say 20-22 PSI V one with 40 PSI...the lower pressure tyre just glides over a sharp rock whereas the 40 PSI just bounces.

So I lower my pressures now every time I get on a rough road, and slow down accordingly to adjust....you can really feel the difference.

Have just returned from the Cape and can tell you people whom I spoke to saying the corrugations were horrendous were all running 40PSI, I thought they were fine and I was running 26 PSI....then went down to 22 when we did the Tele Track.

To each their own, but know which way I will always go!!

LOL, Motherhen.

I agree with most of what The Bantam has said. Particularly about lowering road speed with lowered tyre pressure.

Consider the function of pneumatic tyres. They absorb some of the bumps, hollows and undulations of the road surface. If the roads were perfectly smooth we could run on solid wheels as do trains.

However, as with most things, there is compromise. Very soft tyres absorb more of the uneven track, however being soft introduces some problems. The tyre flexes more creating heat and consuming more fuel. Low pressure can also introduce steering and handling issues. So the manufacturers establish recommended operating pressures based on load, speed, handling, economy, and durability, a satisfactory compromise.

However there can be reasons to sometimes operate outside of that envelope. Most, even you Craig, accept the value in significant pressure reduction for soft sand. Many prefer to reduce pressure to gain more comfort on rough or corrugated tracks and hopefully insure against sharp rocks. In reducing the pressure below the manufacturer's recommended pressure it is also necessary to compensate by proportionally reducing vehicle speed to avoid increasing tyre temperature. However it is personal choice, not a rule. Select the pressure that suits you, provided that the Load, Speed, Pressure relationship remains within safe operating limits. If you belt along corrugated roads at high speeds then you would need to maintain proportionally high tyre pressure.

Yes Craig, it may well increase the tyre stress to a degree but does increase ride comfort. But note that you are not using "tyres as shockies". Tyres at any pressure act more as springs. Shock absorbers act to damp the springs from sustained oscillation. Tyres however do posses some inherent damping.

The Bantam. That's the post that says it all. Spot on. For those who say they have never dropped tyre pressures for corrugated roads, try it. You will feel the difference immediately. No idea what it adds to suspension and other component life, but it must be considerable.
However. If you regularly drop tyres it is essential to have a good tyre pump. Once you get back on bitumen and want to raise your speed, you must increase pressures.

There are two things that are esential for a touring 4wd....a good pump and an accurate tyre pressure guage.

The first one is easy, the second one less so.

Once the first two issues I mention are dealt with, tyre pressures can be reduced with some sort of inteligent reasoning...but not before.


How many of you have weighed you vehicle and consulted the load V pressure tables for your tyres?...the specific tyres that are on your vehicle now.

If you are not reducing your tyre pressures off road, you are almost certainly doing excessive damage to the tracks, making life hard for your self and everbody else.

I have weighed my 4wd vehicle and as loaded.... the load V pressure tables say 28psi......very close to same weight on front and rear axles
I run 30psi on highway.
I carry two sets of stauns, one set to 24psi and the second set to 18psi.

I take the first pressure reduction as soon as I am off the bitumin and wont be going over 80KMH....its only a small reduction but it makes a big difference to comfort and traction.

I'll take the second reduction for soft sand or other situations that need more traction or less ground pressure. and limit myself to arround 60Kph


I have had people try and tell me my pressures are too low and my tyres look flat...but they wear evenly and the vehicle behaves.

If you are running way over prerssure......... I guarantee that some posters on here are, your braking performance and road holding will suffer, particuarly in wet weather.

Some vehicles are very intolerant of tyre pressure.....my old mitsui van drove very well sweetly in fact...with the tyres correctly inflated, 4 psi over and it was a pig of a thing.


Weigh ya vehicle and consult those charts folks..that is ya starting point.

cheers

Sorry Mike, but I disagree with your summation of the thread, what it does show is that there is no rule, but only common sense & speed will give you your best protection.

I think "motherhen" said it best, I just can't see travelling long km's over corragated roads can be good for anything at speed?

As you would know, a lot of things can go wrong, even more so if you are towing, to save these things then it seems to me a slower & more cushioned ride (lower TP) will help you arrive without too many other problems outside just your tyres?

Cheers

I have read that thread and looked at the material, I believe it may be over conservative because the tyre companies are reluctant to release any quantative recommendations on load v pressure v speed at reduced tyre pressures and any information they release will be over conservative.

There are openly published load v pressure v speed tables, but they deal with increased load, at increased pressure and decreased speed in heavy vehicle tyres

BUT it is good to see the matter discussed and to get some idea of how the whole idea works.

The fact remaons that load, pressure and speed are inseperably linked.

cheers

I have come to the conclusion that tyre shops know nothing about tyre pressures and can not read a tyre plackard or the " tyre and rim association of australia -standards manual" which they all have coppies of.

In over 30 years of driving and buying tyres, I have not one single time come away from a tyre shop with the tyres correctly inflated to specifcation.
ALWAYS over inflated and often rediculously so.
My wifes factory standard RAV even came back from the dealer with the tyres significantly over inflated last service.

Consider that any vehicle without a clearly ledgeble tyre plackard is unrodaworthy, there is no excuse for a tyre shop to get it wrong on standard fitment tyres.

In general they tend to inflate all light truck & 4wd tyres to 55psi regardless.

When I picked up my 2wd hilux unladen...the tyres where all inflated to 55 psi......it drove and steered like a dray......I took 20psi......20 @#@&! PSI out of the tyres to get them down to specification.

I have worked thru all the recommended tyre pressures for the variuos options in the hilux manual..and they all pretty closely agree with the figures from the load V pressure tables in the standards manual.


There was a time where it was considered appropriate for manufacturers to recommend lower pressures for ride comfort.

In the past ...like back in the 70s, it was common to see differing round town and highway pressures in car handbooks......has anybody seen that in a recent manufacturers handbook or on a tyre plackard....thaught not.

Because back in the seventies we saw a lot of carcase failures in radials, because people did not increase their tyre pressure on the highway, to was was in fact the correct standard tyre pressure as we now find it.

I keep comming back to soo many vehicles not even being at the right starting point.

cheers

Had a very similar experience last month with my new Bridgestones Bantam. Tyre place had them 12 and 8psi (front/rear) above the placard. Even worse, as I found out on Monday when trying to take a wheel off, they set the wheel nuts way beyond the proper torque rating despite me asking them to ensure that they were not overtightened. Even my rattle gun wouldn't budge them. Took it back to get them retorqued but I still can't budge them manually. Yet to try the rattle gun. Could be back with them again later this week I suspect only this time they can just loosen them and I'll finish them off. Lucky for both of us that I didn't get a puncture in a remote location.

Yeh and people wonder why there is a spate of wheel stud failures.

Damn there are some meatheads out there.

OH...one thing if you havent got one....go get ya self a big 1/2 inch breaker bar and an impact socket to match ya wheel nuts.

I carry one in every vehicle now and that is what I use as a wheel brace

cheers

Me too Bantam. Plus I also carry a torque wrench and tighten my lubricated wheel nuts to the manufacturer's specification.

Any particular brands of breaker bar you blokes suggest? Just did a quick search and one bloke was not impressed by his Sidchrome.

Oh yeh...I've never been impressed with Sidchrome..even less so these days.

I baught mine from supercheap...
so many of the fancy brand name spanners are nothing nore than rebranded generic items these days.

The better generic stuff is everybit as good unless you are going up the price range into the top shelf esoteric brands that are still made in places like germany and sweeden

I also carry a good length of pipe in the tool box is has many uses

cheers

Hi Bazooka,

My breaker bar/wheel brace is telescopic, 500mm long when extended.
It is a solid type, without a swivelling joint for the socket. This type does not allow the socket to twist off line and provides handle offset to clear the rim & tyre.



Mine came with the vehicle. Not easy to find on the web but here is a reference to a source.

My torque wrench is 400mm long. I prefer not to use it to undo wheel nuts, only to torque-up.
My wheel studs & nuts are always lubricated with Loctite Antisieze to ensure torque accuracy and ease of removal.

Thanks chaps. Plenty of choices. I usually just give my nuts a squirt with WD40 but I'll have a look at the Loctite.

WD40s not got much body in it.

There are lots of things you can put on wheel studs...there are plenty od antisieze compounds ot there....and frankly we should all have a tube...a little goes a long way.

A little good quality waterproof grease will do the job just as well......blue grease is a good thing.

cheers

Technicaly, if your tyres are not inflated to the pressures on the tyre plackard the vehicle is unroadworthy.

How far the coppers or the insurance will take that is anybodies guess?

food for thaught?

cheers

Sing up sister, I don't think they heard you at the back.

It is a proven fact and for all road surfaces, lower tyre pressures and therefor lower road surface pressure and lower speeds reduces damage to roads.

The harder the tyre and the faster it hits, the bigger it makes the pot hole ot whatever road imperfection.

The main reason heavy transports are limited to the loads they are....it to reduce damage to the roads, the tyres, axles, suspensions and the trucks themselves ar capable of carrying way more.

Tread lightly and go quietly and life will be better for us all.

cheers

x2
A couple of months ago, we were out in the NW of NSW.
At one camp site, a truckie told us that for them (a big company doing a lot of outback travel), tyre pressures were 100psi on blacktop, 50psi on unsealed.
The road out to Camerons Corner was very badly corrogated beyond Waka Stn. And the ranger's comment was "Yeh, tyre pressuress too high, too much speed. We'll get another fatality out there this year like every other year as the 4WDs with CTs rush through"
Cheers
Andrew and Jen

I don't run Geolanders, I run the Perelli Scorpions in AT....not much between the two and two of the best all round all terains on the market.

BTW...it can be a little tiresome trying to get load V pressure tables out of manufacturers or tyre dealers...BUT the generic load V pressure tables in the wheel and tyre manual are pretty much spot on.

as long as you look up the correct tyre size, carcase family and ply rating.

It all comes down to air volume, with maximum pressure limited by carcase type.

And it is all pretty much standardised.

Our vehicles are held up by the air in the tyres, the tyre simply contains it........may be a little over simple but that is the physics

As I may have mentioned....I have looked up 3 tyres I could run on my existing rims.....all 3 tyres are about the same diameter and tread width or at least not massivly different.....because they are different tyre families and that causes them to be different shapes and different air volumes the correct tyre pressure for load in my vehicle is very much different for the 3 tyres.

Get those tables and weigh that vehicle.

cheers