Tyre Pressures...

[ROnEM]

Hi,

Has the 5 wheels on the van balanced the other day and the guys at the tyre centre said that I should run the van tyres at about 40 PSI for the van and about 38 PSI for the Cruiser as we are about to do about 3,500 kms - but only on bitumen. For off-road he suggested mid to high 20s (PSI) for both car and van.

Looking at the compliance plate on the van it says tyre cold pressure 200 kPa (29 PSI) and maximum load 225 kPa (32 PSI).

As a note, the manager has done the Gibb River Road twice with his van without issue and another staff member has also done the full lap of Oz in his Eagle.

Given that these are VERY different numbers on the compliance plate from what the tyre centre team said, what should I believe?

Cheers,

Rohan

 

[Xpandafan]

Sounds reasonable. But why not do the 4psi test. Take pressure cold and then immediately after about 100km on the Tarmac take it again while hot and if it's 4psi higher you're OK. More than that and you're under inflated. Less than 4psi increase you're probably over inflated. (With LT tyres on your OB you could change the figure 4 to say 5 or 6.)

 

[ROnEM]

Thanks Xpandafan - will reset pressures tomorrow. Not worried about the Nitrogen being mixed with more diluted (76%) nitrogen anyway!

 

[straydingo]

Car manufacturers commonly understate tyre pressures - they are concerned with passenger comfort not tyre wear.
Tyre mobs in my opinion are the ones to listen to as they care about getting the best out of the tyres.
I'm guesing Jayco falls in with the car manufacturers ??

edit: thinking about it today though - With higher pressure a trailer would tow a bit harsher and bounce around a bit more wouldn't it? But softer would sway a bit more?

 

[ROnEM]

I'm guesing Jayco falls in with the car manufacturers ??

straydingo - I have not seen any cars held together with silicon yet. Do they have a new lightweight fuel efficient vehicle the doubles as a leak proof water craft coming?

 

[Antman]

Hi,

Looking at the compliance plate on the van it says tyre cold pressure 200 kPa (29 PSI) and maximum load 225 kPa (32 PSI).

Just a thought on this and I will check ours over the weekend. My father in law and I have similar vans but different tyres whilst being the same size tyres. I would think that Jayco probably get what ever tyres they can at the time. Would they change the compliance plate to suit different brands?

As said, i will check our compliance plates over the weekend and see if the pressures are the same across the two vans etc.

Ants

 

[relgate]

I've always kept my trailer tyres low to cushion etc. I figure there is much less sideways force on a trailer tyre too.

 

[Xpandafan]

I've always kept my trailer tyres low to cushion etc. I figure there is much less sideways force on a trailer tyre too.

For what it's worth, the downside to lower pressure is more rolling resistance, poorer handling such as braking in the wet, etc., poorer fuel economy, and faster tyre wear. Better to rely on the suspension for cushioning rather than the tyres.

 

[cruza driver]

Hi,

Has the 5 wheels on the van balanced the other day and the guys at the tyre centre said that I should run the van tyres at about 40 PSI for the van and about 38 PSI for the Cruiser as we are about to do about 3,500 kms - but only on bitumen. For off-road he suggested mid to high 20s (PSI) for both car and van.

I agree with all these pressures and this is what we run but with 40psi in the Cruiser too. And have nver had a problem.

And on the dirt (Ood trk and Painted desert) 28psi in the van 32 rear cruiser 30 on the front

 

[Matty4]

On road in the van I run 40psi as well.
On smooth dirt roads I never bothered lowering pressures but once onto corrugated roads I played with the pressures and finally settled on 22psi.
I'll up the pressures in the Jeep from the current 36psi to 40psi when I start towing.

 

[ROnEM]

Interesting - the tyre centre checked the pressures in the van tyres and they were all at 38 PSI. I have not touched them as the van is only 4 weeks old, so either the dealer has inflated them pre-delivery or the factory is sending them out with higher pressures than on their own compliance plates.

 

[relgate]

Interesting. I'm gonna go and check mine too now. I seem to recall the dealer quoting something around 34psi. Mine is also only 4 weeks old

 

[relgate]

Ok, so mine (17'OB) are all reading 33psi one month and about 1300km after delivery. I'm not sure I have any reason to add any more psi

 

[BUSH PALACE]

Hey guys just remember you should have LT tyres fitted with a load rating of 109+ so you can use up to 60psi running your tyres at a lower pressure ie below 40 psi you run the possibility of overheating the sidewalls which you can only see internally which can cause blow outs down the track . Use a lower tyre pressure at a lower speed for dirt driving is ok where the tyres can mould into and over rocks stopping punctures just watch your speed and as for using your tyres as suspension dont worry about it thats why we have springs / shockers underneath ...
just putting it out there if your interested ...

cheers Russell

 

[cruza driver]

I agree BP we drop our speed on the dirt to enjoy the scenery.

 

[ROnEM]

BP - looks like mine are not light truck tyres. Only have a 105T rating and on the tyre wall it says not to inflate beyond 40PSI.

Factory fitted Savero A/T Plus GT Radial 235/75 R15 105T

 

[relgate]

BP - looks like mine are not light truck tyres. Only have a 105T rating and on the tyre wall it says not to inflate beyond 40PSI.

Factory fitted Savero A/T Plus GT Radial 235/75 R15 105T

Same here. "do not inflate beyond 40 psi"
I also notice they're made in indonesia

 

[Xpandafan]

Checked with old time motoring expert yesterday as I was checking my van tyres (40psi). He subscribes to the 4psi test detailed in my earlier post. Use decent tyre pressure gauge and take reading cold and then immediately after 100kms when hot. If its 4psi higher when hot your pressure is correct. If higher than 4 you're tyres are under inflated. If the difference is less than 4 you're over inflated. I think it's still a rule of thumb that NRMA and RACV use.

 

[Capt. Gadget]

Mine are Savero A/T Plus GT Radial 245/70 R16 111T Max Load 1090 kg at 340kpa (49psi) Max they were at 34psi but I have bumped them up to 38psi will check them when warm tomorrow and see what the difference is

 

[ROnEM]

As an update - ran the van tyres at 40psi all the way up to Qld and back for a total of 3,500km - no dramas. Stopped after about an hour/100km on the road for the 1st few days and pressures were fine, so will stick with the 40psi on the blacktop.

Also advised by the tyre shop to run the Cruiser's tyres at the same pressure. Again, no issues on the Qld trip. Just had the Tug serviced - 1st thing I have to do is put air back into the tyres after the dealer dropped them to 32psi.

Rohan