Tyre pressures (Twin axle)

[lishka]

I stopped off at a local garage just to double check the tyre pressures, I always fill them to the max psi stated on the tyre wall (45psi)
However as I was topping one of them up I noticed it said max 35psi ?
All 4 tyres are the same brand (nankang) their all 175/60R 14 79H their all 437kg max load, the only difference I have noticed is the 45psi say toursport 611 on them and the one 35psi says EX-601 ?
Now after noticing this I altered them all to 35psi but this felt uncomfy down the road, would it be safe / safer to have 3 at 45psi and 1 at 35psi?

 

[BrianS]

Tyre pressures should be set as per the caravans / manufactures hand book the maximum pressure is a safety maximum when sealing the tyres on to the rim on fitting etc. If you set them at 45psi cold then it will be greater when they are hot!!!

 

[ProfJohnL]

As Brain states, tyre pressure should be set as per the caravan manufacturere specifications. Whilst Singel axle caravans do tend to have pressures in the 45 to 50 psi, Twin axles will be somwhat less as more tyres are carring the load, so pressures in the region of 30 to 40 psi would not be unexpected.

 

[Gafferbill]

…….you cannot have different tyre pressures on the same axle as this would be dangerous.
35 psi is likely to be OK in all 4 tyres of your twin axle but definite advice cannot be given on a forum.

This guide should help…………..
http://www.tyresafe.org/images/campaigns/caravan_tyre_safety_leaflet.pdf
　
From the tables you will see that it quotes tyres with a load index of 79 should have a
pressure of 36psi for an axle load of 874kgs.

Pressures could be less for lighter axle loads depending on what caravan you have.

 

[Dustydog]

Hi Lishka
What make and model do you have?
My Wyoming TA with just a MTPLM of just under 1700kgs has a recommended tyre pressure of 29psi. Usually the cararvan manufacturer includes the tyre pressure information on the weight plate.
45psi seems extraordinarily high. As the others say, the correct psi for your unit is in the owners manual NOT what the tyres maximimum pressure is!

 

[SirRogerFFS]

When we bought our van new 2 years ago the dealer had made a note of tyre pressures being 65 PSI I thought this was far too high so I checked as somebody has already said near the weight plate it will give you manufacturers figure mine is a Sterling Elite Searcher on a T/A 45PSI I hope this is some help
Sir Roger

 

[otherclive]

The max pressure quoted on the sidewall is the maximum when the tyre is at its max load which is dependant on the Load Index. The seating pressure is generally lower and is defined as such on the sidewall. Although for twinaxle low LI this might vary If all your tyres have the same Load Index them you should use the van makers stated pressure. If one has a different LI then there are tables which give operating pressure versus load for different LI but nowadays these tend to be make specific. My tyres are indexed well above their max load when on the van but Bailey and Firestone Tech Dept supplied operating tyre pressures. So they now run at 55psi compared to their max at full LI of 65psi.
Many doubts and I would buy a new tyre to make sure the axle pairs have the same LI and operating pressure.

 

[lishka]

Thanks foral the advice! Ive just dug the service book out for my 2007 Lunar quasar FB and it seems they recomend a tyre size of 175/60 R14 and a pressure of 36psi
As daft as this might seem I didnt think of checking the handbook and thought the information on the side of the tyre would be correct and sitable for my van, so thanks very much for bringing this to my attention.
After reducing the pressures to 35psi I didnt feel as sturdy however this was maybe just physiological!
Time for a good look through the service and handbooks I think, every days a learning day!!