Tyre pressure

This site has an option for single or twin axles however does anyone know if you put in the weight for 1 axle or the 2 combined (so for me it would be 1600kg or 3200kg as I have a tag axle MH)?

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For a Tag axle it has front, axle 1 and axle 2. Input each individual axle weight.
 
Not on mine. Am I doing something wrong?

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Don't think so, I get the same page and options.

I have to say I get confused by this site, they state ....

"CP-type tyre construction enables the use of higher inflation pressures to provide resistance to the difficult conditions of use encountered on motorhomes. Therefore, when CP-type tyres are fitted on the rear axle in a single formation set the inflation pressures to 5.5 bar (80 psi) for all loads."

However, I'm not sure what they mean by "difficult conditions of use". I have CP rated tyres fitted so obviously get a result of 80psi on the rear axle, if I change the rating to "C" with the same tyre size and axle load I can drop the pressure to 59psi. 🤔🤔
 
They have updated the website since I last used it but I got a result.

On a tag axle both axles are identical and usually have a rating of around 1500 Kg. I just inputted my front axle weight and the weight of one tag axle and got the correct pressures.
 
Well im leaving mine at 65psi as having double back wheels and there will never be 3 ton of lib books in it, anyway the tyres wear even across the tread, just a pity there expensive if you buy new,
 
They have updated the website since I last used it but I got a result.

On a tag axle both axles are identical and usually have a rating of around 1500 Kg. I just inputted my front axle weight and the weight of one tag axle and got the correct pressures.

If I do that I get 65psi for the front but only 40Psi for the back...which seems a tad low to my mind

If I add the 2 axles together and put that in I get 65Psi all round!
 
If I do that I get 65psi for the front but only 40Psi for the back...which seems a tad low to my mind

If I add the 2 axles together and put that in I get 65Psi all round!
Look at the photo above your last post of the Cathargo tyre pressures for various loads. Therre are some low pressures on that chart. You have not said what size tyres you have.

Edited to add that when I put 4 new tyres on the back 2 axles, I used Commercial Agilis and not CP tyres.
 
If I do that I get 65psi for the front but only 40Psi for the back...which seems a tad low to my mind

If I add the 2 axles together and put that in I get 65Psi all round!
That does sound low for the rears, but bearing in mind the rear axles are sharing the load I would expect the rear tyre pressures to be lower than the fronts unless the weight distribution is very uneven.
 
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That does sound low for the rears, but bearing in mind the rear axles are sharing the load I would expect the rear tyre pressures to be lower than the fronts unless the weight distribution is very uneven.
My tyres are 225/65 R16 CP (C on the back axles). Tyresafe give the pressures as Front 62 psi, Rear 44 psi.

I run at Front 65, Rear 50. I added a few pounds as I have alloy rims which can very slowly bleed off a bit of pressure over time.

At the moment my van is totally empty as I have put it up for sale. With nothing on board it rattles a lot more when I drive it. I am thinking of reducing the tyre pressures as it may put prospective buyers off a bit. :ROFLMAO:
 
Look at the photo above your last post of the Cathargo tyre pressures for various loads. Therre are some low pressures on that chart. You have not said what size tyres you have.

Edited to add that when I put 4 new tyres on the back 2 axles, I used Commercial Agilis and not CP tyres.

225/75R16CP Michelin ones
 
225/75R16CP Michelin ones
If you are happy at that pressure then stick with it.

You could always try an old fashioned test to see what contact you have with the road. Find a bit of new smooth tarmac. Measure the width of tread across the tyre. Put a chalk mark across the tread and roll the wheel forward a revolution, then check the chalk mark on the road. It should be the same length and evenly distributed as the tyre. If the mark is shorter, you are over inflated. If the mark is fainter in the middle, you are under inflated
 
That tells me 53psi front and 80psi rear but for full plated loads. But actual rear is 1600, and for gross vehicle weight I can only put 1700kg on rears….so still unsure.
If you contact them then they will calculate the correct pressures for you
 
If they are Michelin CP, tech support will only calculate the front axle and tell you 80psi on the rear.
That’s exactly what they did. For a van with a large rear overhang and all the storage at the back that may make some sense. But with a van heavy at the front and with a low allowable max load at rear I can see no logic in it.
 
That’s exactly what they did. For a van with a large rear overhang and all the storage at the back that may make some sense. But with a van heavy at the front and with a low allowable max load at rear I can see no logic in it.
The only explanation I could get was that CP rated tyres are reinforced, particularly on the sidewalls, to help prevent degradation when standing for long periods. To achieve this Michelin say they have to be kept at max pressure i.e. 80psi. I will be switching to Continentals next time as their camper tyres can run at lower (more comfortable) pressures. One option might be to run the Michelins at the equivalent C rating pressure on the road and pump them back up to 80psi when left for long periods ?
 
The only explanation I could get was that CP rated tyres are reinforced, particularly on the sidewalls, to help prevent degradation when standing for long periods. To achieve this Michelin say they have to be kept at max pressure i.e. 80psi. I will be switching to Continentals next time as their camper tyres can run at lower (more comfortable) pressures. One option might be to run the Michelins at the equivalent C rating pressure on the road and pump them back up to 80psi when left for long periods ?
Michelins approach makes sense for the typical Motorhome user I would say ...

How many people actually check their tyre pressures on a regular basis and/or adjust them for differing loads and circumstances (very few. Cue the "you should check before each journey and weekly" responses, but we live in the real, failed, world).
And what proportion of Motorhomes spend 90% of their life stationary on a driveway or storage facility - and 90% of the remaining 10% stationary on a Campsite? (the great majority of them I reckon - just need to look at the mileages of ones for sale ... 10,000 miles on a 10 year old van for example).

For THOSE users, the features of the Michelin 'Camping' spec tyres seem right and maybe the design of these tyres means they should actually be run at 80 PSI in use as well as when parked?
I don't know. Does anyone other than Michelin? Why should an individual user know better than the maker of the product? Michelin will say nothing other than 80PSI. They presumably have a reason for this stance I would imagine?

FWIW, I use Michelin Aglis Tyres on my Motorhome, but I run the Aglis Cross-Climates as they are (IMO) much more suitable for my location, being all-season tyres. The Aglis Camping Tyres are designated as 'Summer' Tyres. Come the Winter - or in Scotland, most of the year (seriously) - when average temps fall below 7C, the use of Winter Tyres is recommended, and this is where the Cross-Climates come into play rather than having to have 2 sets of tyres. It is not just about ice and snow, but temperature as well.

The Aglis Camping Tyres again are designed for the typical Motorhomer - the ones that only use their vehicles in the summer and usually head to warmer places to boot. All-year users should (again, IMO) look to fit all-season tyres.
 

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