Recommended tyre pressures.

[Thingy]

On the caravans plate, its gives as we know various weights and presumably in all cases tyre pressures. But how grey an area is this.

Presumably, these pressures refer to the vans original tyre i.e. brand and size. But I know many people put other brands on the caravan when new ones are needed. In my case 65 psi is stated on the plate, but this does seem high and I notice that after a run the caravans tyres are somewhat warmer than the cars which I was always taught was a sign that pressures were too high. When we ran trucks in Italy, we would reduce pressures during the hottest summer months and we did have less blowouts once we adopted this practice. We had over 100 trucks in Italy alone and it was a marked decrease in incidents.

How many of you stick to the plates recommended pressure. Anyone else notices a temperature increase? Do you run on lower pressure than the plate? If so, by how much?

 

[Jaydug]

Yes - I've remarked on this and other forums how my caravan tyre pressures always increase more than the car's tyres after about ten miles of running. Cold - I have 2.4; 2.8 and 3.6 on the van. After some miles in warm weather they go to 2.6; 3.0 and 4.1 My caravan tyres are the same make and grade as when the van was new.

 

[Gagakev]

Van tyres set at 65psi.
Last summer(yes we did have some) pressure on motorway went to 73psi and and the temp went up approx 15 degrees from start, cant remember exact temps though sorry.
Oh I have the tyre pal system fitted.

 

[camel]

On the caravans plate, its gives as we know various weights and presumably in all cases tyre pressures. But how grey an area is this.

Presumably, these pressures refer to the vans original tyre i.e. brand and size. But I know many people put other brands on the caravan when new ones are needed. In my case 65 psi is stated on the plate, but this does seem high and I notice that after a run the caravans tyres are somewhat warmer than the cars which I was always taught was a sign that pressures were too high. When we ran trucks in Italy, we would reduce pressures during the hottest summer months and we did have less blowouts once we adopted this practice. We had over 100 trucks in Italy alone and it was a marked decrease in incidents.

How many of you stick to the plates recommended pressure. Anyone else notices a temperature increase? Do you run on lower pressure than the plate? If so, by how much?

One hundred trucks in Italy at any one time, what company was that?

 

[Thingy]

Murfitts out of Whittlesey and Ely. Ran road trains, tilts and megas. Also had a fleet for both short sea aka Benelux and commie block as it was back then. I worked both long sea and then later commie. Murfitts also had McCains frozen in livery.
The 100 units also included intermodal from the Milan railyards.

 

[Dodger524]

I did find a website with details of calculating tyre pressure according to tyre size and caravan weight and if I can find it I shall post the link here. As I do not load my caravan to maximum weight I am able to reduce my tyre pressure from 60psi to 55psi. Theoretically tyre pressure should be adjusted to suit ambient temperature before starting a journey but I guess most of us just check every few months. The pressure will increase during use as the tyre temperature goes up due to friction but the tyre is designed for this and no pressure adjustment is necessary.

Here's the link to the article of pressures in caravanchronicals.com.

 

[camel]

Murfitts out of Whittlesey and Ely. Ran road trains, tilts and megas. Also had a fleet for both short sea aka Benelux and commie block as it was back then. I worked both long sea and then later commie. Murfitts also had McCains frozen in livery.
The 100 units also included intermodal from the Milan railyards.

Thingy,
I know Murfitts or did know Murfitts when I was in the industry, I think Murfitts ran close coupled outfits long before Stobart started to run them,

 

[Thingy]

Lets say for example the caravan is saying pressures should be 60 psi, and the max pressure on the tyre is 65. In warm weather with a heavy caravan there is a possibility of these pressures within the tyre increasing to near maximum.

For my next trip I am going to follow my own thoughts and reduce pressures by 5 psi and check the tyre temperatures en route. A further thought is that a softer tyre will make a gentler ride for the caravan but going to soft can increase the likelihood of a snake. It is a definite fine balance and care will be needed.

 

[WoodlandsCamper]

Tyres are normally marked with the maximum pressure for a maximum load The caravan MTPLM is either carried on 2 tyres or 4 tyres depending if it is single axle or twin axle respectively and is shared out equally. The recommended pressure in each tyre is simply the ratio of the maximums, ie

Tyre maximum pressure multiplied by (MTPLM divided by number of wheels) divided by tyre maximum weight.

Contrary to what has been stated previously in this thread I would have thought that an under-inflated tyre would get hotter than a correctly-inflated tyre as it would flex more and generate heat caused by the flexing movement.

 

[WoodlandsCamper]

Lets say for example the caravan is saying pressures should be 60 psi, and the max pressure on the tyre is 65. In warm weather with a heavy caravan there is a possibility of these pressures within the tyre increasing to near maximum.

As all pressures should be measured prior to the start of a journey, ie when 'cold', then any heating during use should be well within the tyre's design safety limits. No deviation from any recommendations by the manufacturers should be made.

 

[Thingy]

Thingy,
I know Murfitts or did know Murfitts when I was in the industry, I think Murfitts ran close coupled outfits long before Stobart started to run them,

Murfitts was quite a progressive firm back in Mick Murfitts day and he was a hell of a guy to work for. Things took a definite downturn when he "finished" and the firm slid into obscurity and then history. Its the only HGV firm I ever worked for that we werent continually pushed to be somewhere, and was simply a matter of let us know when you are there. We were also the first firm to have the "cab fax" although that was used by the lads to arrange the weekends drinking

A further first was that we were the first firm licensed for Cabotage, although that meant you could be away from home for weeks. With this in mind the firm would allow drivers once empty to do a bit of distance for themselves to be with other drivers for the weekend rather than sleep where you stopped. Those days are long gone now.

Mick would also allow drivers to take spouses/girlfriends along which alleviated the pain somewhat.

 

[camel]

We ran on TIR plates in the late 70's I think that was before Cabotage came in loosing touch these days but I still read the Commercial Motor each month,

 

[otherclive]

On the cars the tyres , along with oil, water etc are checked weekly even though they have TPMS fitted. I only check when the tyres are not subject to sunlight on one side, and shade on the other. The caravan is check monthly and prior to leaving on a trip. Again I only check when the tyres are not subject to light and shade on respective sides.

Re tyre pressure and caravan weight I have found most manufacturers will give you the inflation pressure for a number of weights. If not, the accepted formula works out quite well as long as you are not running high pressure high load index tyres at a very low load.