Tyre Pressure

[wrx fifer]

as the title states do the tyres have the recommended psi on them? with not having a book, or any information on it, not even sure of model number at this point to be honest it,s a 4 wheel hobby exclusive, as only picked it up and delivered it to friends garage and left and will be going up this week to work on it, just wondered if anyone would know a rough psi for them all?

 

thanks Grant

[OWOMW]

The tyres will be stamped with the MAXIMUM psi, but not a recommended psi.

Also on the tyres will be stamped a maximum load, in kilograms.

 

Failing any other information there is a formula that you can use to get a fairly accurate tyre pressure.

 

You will need the maximum weight of the van (MTPLM) which will be on a plate on the van, sometimes near the door.

 

Divide the MTPLM by 4 to get the actual load on each tyre.

 

Divide the actual tyre load by the tyre's maximum load, then multiply this by the tyre's maximum psi

 

so,

PSI = (MTPLM/4)*MAX PSI / MAX LOAD

 

Example:

MTPLM = 1800 kg

MAX PSI = 50 psi

MAX LOAD = 500kg

 

PSI=(1800/4) x 65 / 500 = 45 psi

[wrx fifer]

thanks that's a good sum, will write that down somewhere for future reference!

[jadatis]

In addition to this .

Going from the fact that most Caravans are loaded to their MPVW ( max permissable vehicle weight) or even a bit overloaded, you can first add even up to 25% first to the MPVW before doing the calculation.

 

Then even no bumping so screws come loose from woodwork, and this gives as much possible reserve for things like, pressure loss in time, unequally loaded R/L, misreadings and yudgings of weight and pressure .

 

If then advice pressure is a bit above the minimum pressure needed for the maximum load ( maximum load xxxx kg AT yyy psi(cold)" then its allowed even by the stikt system of American TRA up to 10 psi.

 

Then if the 4 tires are on one ( imaginary) axle you have to use the maximum load for Dual instead of Single wich is most 2 Loadindex-steps lower then Single maximum load.

 

You can also use spreadsheet I made, in wich I use a little different formula, and standard the reserve to the assumed load.

https://onedrive. live. com/?cid=A526E0EEE092E6DC&id=A526E0EEE092E6DC%21348

First download a spreadsheet to your computer by RIGHT-CLICKING and then choose DOWNLOAD, other means go wrong .

Then after download and eventual virus-check open it in Excell programm on your computer, but Open office CALC can work with it too.

[beejay]

as the title states do the tyres have the recommended psi on them? with not having a book, or any information on it, not even sure of model number at this point to be honest it,s a 4 wheel hobby exclusive, as only picked it up and delivered it to friends garage and left and will be going up this week to work on it, just wondered if anyone would know a rough psi for them all?

 

thanks Grant

 

Hobby caravans have a recessed sticker on the wheel arches showing tyre pressures.

 

The model type will be on the manufacturer's plate on the front left side.

 

Try the Hobby owners club web site for information.

 

 

In addition to this .

Going from the fact that most Caravans are loaded to their MPVW ( max permissable vehicle weight) or even a bit overloaded, you can first add even up to 25% first to the MPVW before doing the calculation.

 

Then even no bumping so screws come loose from woodwork, and this gives as much possible reserve for things like, pressure loss in time, unequally loaded R/L, misreadings and yudgings of weight and pressure .

 

If then advice pressure is a bit above the minimum pressure needed for the maximum load ( maximum load xxxx kg AT yyy psi(cold)" then its allowed even by the stikt system of American TRA up to 10 psi.

 

Then if the 4 tires are on one ( imaginary) axle you have to use the maximum load for Dual instead of Single wich is most 2 Loadindex-steps lower then Single maximum load.

 

You can also use spreadsheet I made, in wich I use a little different formula, and standard the reserve to the assumed load.

https://onedrive. live. com/?cid=A526E0EEE092E6DC&id=A526E0EEE092E6DC%21348

First download a spreadsheet to your computer by RIGHT-CLICKING and then choose DOWNLOAD, other means go wrong .

Then after download and eventual virus-check open it in Excell programm on your computer, but Open office CALC can work with it too.

 

 

Totally unnecessary and very confusing. Dual tyre ratings are for tyres fitted as a coupled pair on the same side not across an axle.

Caravans will not operate at the maximum speed rating of the tyres fitted which will be at least N (87mph) therefore the load rating will be more than adequate if they match or are no more than 110% of the caravan MAM (or MPTLM).

Edited August 18, 2014 by beejay

[jadatis]

The advice I calculate gives as much possible reserve with still no bumping.

This is other advice then the caravan-makers give wich is the lowest wich dont give damage to tyres if the given loads are right and not unequally devided R/L.

 

I Know that for lower speed the tyre is allowed more deflection so lesser pressure for the same load .

Even did research about howmuch about it.

But why would you give a tire yust enaugh pressure for the load and speed, with the risk of misyudging weight and misreadings of pressure wich would make the tyre damage ?

 

If TS 4 wheels are on one axle and so no Tandem axle. then the Dual load maximum load should be used.

[wrx fifer]

thanks again guys and yeah when I was up having a look at it today I noticed the small recessed plate saying 2. 5 bar I think, but I will sort all that out after I have fixed some other stuff before I remove it from the unit, will get all the work done.

thanks again very helpful!