tyre pressure

blaze · Guru

tyre pressure

jimricho · Guru

Check with the supplier of the tyres as it's possible (but not definite) that in trying to make them look inflated you could be over inflating them. The tyre wallah should be able to suggest a pressure based on the axle load.

(edit - typo, why can't I get it right the first time? disbelief

)

-- Edited by jimricho on Wednesday 24th of November 2010 06:24:50 PM

pricey43 · Guru

We have a 16 ' pop-top with light truck tyres.

We have ours on 45-50 psi.

justcruisin01 · Guru

blaze wrote:

What pressure are we all running in our van tyres. I took off an old set of cross ply tyres today and update to radial light truck tyres and was surprised at the pressure needed to make them look inflated
cheers
blaze
ps
have a 16 foot van, single axle

Blaze , Cross ply tyres, how old were they? can,t even remember the last time I fitted one in the trade.

blaze · Guru

Ive change a few crossply and old rag tyres in my day too, have memories of having to burn old truck tyres off rims because no amount of force would break the bead.
Looks like 55 pound pressure will be about the required pressure for these tyres (8 ply light truck), used to run the old crossplys at 40, that stiff in the walls there was no bulging. I did have some serious discussions with the tyre company (purchased all my tyres and batteries there for the last 30 plus years) as to the quality of their tyres but have been asured they will do the job fine
cheers
blaze

Smokeydk · Guru

I had a read of the new vans tyres and it recommended 36psi..

Cupie · Guru

You have opened up a can of worms here.

I have observed forum threads over the years on this question.
We get input from a range of people who have either experience based views and some that will produce complicated formulas to arrive at an answer. Who knows which is right.

For my part, I started by looking at the 'compliance/manufacturers' plate on my van. For my tandem axle 21'6" van it says 200Kpa (29psi or 2bar). This seemed a bit under inflated to me so I kept going back to the manufacturer who stood by their recommendation. I noted that later model similar vans had a higher recommended presure. Maybe different suspension settings?

I find that the local tyre people have as many views as there are local tyre people.

These days after never having a tyre failure over >150,000km, I have finally settled on 230Kpa (33psi). This is a bit over the van manufacturers specs but well under the tyre specs & the van rides beautifully. I certainly wont go higher.

I say, if in doubt under inflate & check tyre temperature regularly.

Hope this helps.

-- Edited by Cupie on Wednesday 24th of November 2010 10:11:57 PM

blaze · Guru

Bit like bottoms isnt it, been in lots of debates myself over tyre pressures for a particular driving surface etc. My new light truck tyres are 8 ply with a load rating of 850kg's at 65 psi. They look ok at 55psi so I will start there but will keep an eye on temp and pressure increase as I cross the nullabor in late january. They will certainly give the van a better ride at 55psi than the old ones did a 40psi.
cheers
blaze

Cupie · Guru

Yes your right about bottoms & I hope you're right about the improved ride.

A mate of mine followed me across the Kimberley area & mentioned how my rig was tracking nicely & his was bouncing all over the road. He reduced his tyre pressures & solved his problem. We both had tandem vans.

I'd still be looking at around 40psi max and if van stability/ride is an issue and maybe check other things such as ball weight & weight distribution.

Thank god we're all different hey?

jimricho · Guru

Over Inflation will kill tyres on hard rocky roads. Unfortunately the same conditions as "hard rocky roads" can be encountered anywhere, a rough bit of highway, a nasty pot hole, road works and detours, etc etc.

Several years ago I was having a conversation in a caravan park with a tyre wallah from Adelaide who said that he often sees evidence of over inflation on vehicles that have been up to Flinders Ranges, in the form of small star fractures on the inside of the tyres.

I don't know how valid this is but I've heard that if you check your tyre pressures cold and then after a long run, and if the rise in pressure is greater than 4 psi it could mean that the tyre is under inflated.

Jim

PS: A couple of questions for you... what is the ATM (aggregate Trailer Mass) or GTM (Gross Trailer Mass) of the van (should be on the compliance plate and/or the rego certificate, please state which one, ATM or GVM, you're quoting), the maximum load of the tyres, and the max cold pressure at that load. The last two are on the sidewall of the tyre.

-- Edited by jimricho on Thursday 25th of November 2010 07:41:05 AM

ozjohn · Guru

The safest way to detirmine correct tyre pressures is the old 4 PSI rule.
For a 16' Single axle van start at around 50 - 55PSI and after around 100Km of towing check the tyre pressures. If the pressure has risen 4 PSI then the pressure is correct. If the pressure is higher then the tyre is under inflated and more air should be added. If the pressure is lower then you can let a little air out.
Note: On extemely hot roads then work on a 6PSI increase in pressure.
If the pressure is a little to high that's OK as I always reckon it's better to wear them out than blow them out. On my 16'6" single axle van with 1600Kg on the wheels I run 60PSI.
The vast majority of vans on the road have under inflated tyres especially tandems.
Also many vans are supplied with tyres that have an under rated load capacity.
Cheers, ozjohn.

Footnote: Tyre pressures shown on van compliance plates are almost always for an unloaded van and need to increased substancially when the van is loaded and water tanks full. Also don't forget to balance the wheels. More than 70% of vans on the road haven't had their wheels balanced, even from new.

Pejay · Guru

Hi Blaze, we are running 40psi on the Nissan (Kuhmo tyres A/T) and 50psi on the van, as they are light truck tyres - also Kuhmo.