Weighbridge and tyre pressures reality

W

Woodgates

Joined
Oct 19, 2013
Posts
63
Likes collected
124
Location
East Yorkshire
Funster No
28,641
MH
Vantage Sol
Exp
Since 2003
I recently used the dynamic scale weighbridge at King George Dock in Hull with the following results:

Front 1810. (Plated at 1850)

Rear 1550. (Plated at 2000)

Gross 3360. (Plated at 3500)

This was in holiday trim with 2 adults included (for a week), ie. full fuel tank, full fresh water, full lpg underslung, empty grey waste, empty cassette. We don’t carry bikes or bbq but do have mountain walking gear and then general clothing and food of course! etc.

Contacted Continental Tyres for their recommended tyre pressures

Front 3.5 bar (50psi), Rear 3 bar (45psi)

This made for a really comfortable ride compared with the factory set up of 60psi all round.

Vantage Sol PVC 6m

Derek
 
Last edited:
That’s interesting my A class is 3650 and recommended pressure is 5.5 bar all round. Drives like we have concrete wheels. I have dropped to 4.5 and slightly better but need to reduce again i think.
 
Simon Meadwell said:
That’s interesting my A class is 3650 and recommended pressure is 5.5 bar all round. Drives like we have concrete wheels. I have dropped to 4.5 and slightly better but need to reduce again i think.
Click to expand...
Do you have Michelin’s? no matter what you weigh in on the axles, they always say 80 psi.. rock hard ride.

I have my fronts at 64psi and rears at 72psi, better but not brilliant
 
jdk62 said:
Do you have Michelin’s? no matter what you weigh in on the axles, they always say 80 psi.. rock hard ride.

I have my fronts at 64psi and rears at 72psi, better but not brilliant
Click to expand...
No Continental campers

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Lenny HB said:
For me Toyo recommend 56psi front (1930kg), rear 69psi (2300kg).
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My Hymer book states 54psi front (2000kg) and 65 psi rear (2000kg).

Just checked the actuals, dealer has put in 72 front and 70 rear. Looking forward to a softer ride🤗 now that I've reduced them.
 
jdk62 said:
Do you have Michelin’s? no matter what you weigh in on the axles, they always say 80 psi.. rock hard ride.

I have my fronts at 64psi and rears at 72psi, better but not brilliant
Click to expand...
I've always dropped a lot more than that based on Continental recommendations.
 
Folkranger said:
My Hymer book states 54psi front (2000kg) and 65 psi rear (2000kg).

Just checked the actuals, dealer has put in 72 front and 70 rear. Looking forward to a softer ride🤗 now that I've reduced them.
Click to expand...
Are you sure as if it has Michilen tyres Hymer will quote 80 psi for the rear.
 
jdk62 said:
Do you have Michelin’s? no matter what you weigh in on the axles, they always say 80 psi.. rock hard ride.

I have my fronts at 64psi and rears at 72psi, better but not brilliant
Click to expand...

That's why I have just bought a set of Conti Campers
 
How does changing the pressure way from tyre or vehicle manufacturers sit with the current law regarding tyre pressure tolerances ?

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jdk62 said:
Do you have Michelin’s? no matter what you weigh in on the axles, they always say 80 psi.. rock hard ride.

I have my fronts at 64psi and rears at 72psi, better but not brilliant
Click to expand...
Michelin quoted me 4.5 bar/ 65psi front.
 

Attachments

Lenny HB said:
Are you sure as if it has Michilen tyres Hymer will quote 80 psi for the rear.
Click to expand...
This is from the Hymer Manual. Am I missing something obvious? Light V Heavy Chassis?
Screenshot 2021-08-03 203854.png
 
I find this a handy reference tool

www.tyresafe.org

Motorhome Tyre Pressure Calculator | TyreSafe

Our motorhome tyre pressure calculator gives you the correct pressures for your motorhome. Check your tyres regularly for your safety.
www.tyresafe.org www.tyresafe.org

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It is interesting that the Tyresafe calculator seems to set rears at 5.5/80 irrespective of load for CP rated tyres, merely adjusting the fronts to a lower pressure.
 
Our Rienza is rear wheel drive Transit base. I really need to ind a weigh bridge if only as a matter of interest. The garage that services it checks and adjust the tyre pressures to 50 psi fronts and 60 psi rears. Being leaf springs at the back it’s a fairly hard ride any way but the Conti Campers seem ok handling wise and have worn well.
I am not sure we’re to find a weigh bridge here. Maybe the VOSA test station. I will look into this.
 
cyberyacht said:
It is interesting that the Tyresafe calculator seems to set rears at 5.5/80 irrespective of load for CP rated tyres, merely adjusting the fronts to a lower pressure.
Click to expand...
Seems to be a ETRTO (European Tyre & Rim Technical Organisation) thing. Apparently in their standards manual have a paragraph that suggests all CP type tyres fitted as single fitment rear tyres on a camper should be inflated to a minimum of 5.5 bar (79 psi), even if the load on the axle is such that the inflation requirement based on the standard ETRTO tables and manufacturer data is lower.
 
I run My Perguot 60 front 65 rear. Still got all my teeth😁

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I have 225/75 R16 116R Continental Vanco camper tyres on my MH. Continental recommended the following pressures.
Gross weight. 3.500 kg
Front axle. 1.850 kg = 3.5 bar. 50.8 psi
Rear axle. 2000 kg = 4.25 bar. 61.6 psi
 
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bigwood said:
Our Rienza is rear wheel drive Transit base. I really need to ind a weigh bridge if only as a matter of interest. The garage that services it checks and adjust the tyre pressures to 50 psi fronts and 60 psi rears. Being leaf springs at the back it’s a fairly hard ride any way but the Conti Campers seem ok handling wise and have worn well.
I am not sure we’re to find a weigh bridge here. Maybe the VOSA test station. I will look into this.
Click to expand...
You could try
https://www.lasmetals.co.uk/

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VOSA now DVSA have virtually no stations with fixed weighbridges as testing facilities outsourced (ATF) HTSH :)
 
I'm running at 51F/70R psi based upon Continental's sound recommendations based on actual axle weights. Ride is fine, grip good. Unlike the concrete, tooth filling dislodging pressures when I collected the van, I was horrified.

The politically correct rear pressure of 80 psi is the position taken by Michelin and other trade bodies for the rears, irrespective of loading. The justification is that MH's run at full loading most of the time (which is largely correct) and spend significant time stood still, so need reinforced sidewalls and full rated pressure to withstand it. There is some merit in these arguments, but I'll take the advice of the friendly support from Conti. The high pressures suggested result in a terribly hard ride and poor grip, as several have noted. I carry the document from Conti showing the pressure/loading table, as a defence in case ever asked at the roadside (unlikely I know).

A bigger problem for me, and I suspect many others with Sevel built base vehicles (Fiat/Peugeot/Citroen), is how to prevent the Tyre Pressure Monitoring system displaying a low pressure warning and dash lights, bleepers etc. I got round this by a local diagnostic company re-programming my BCM module with the pressure of my own choosing, my own Autel equipment wouldn't do that level of detail. Neither would the local Peugeot main dealer, unsurprisingly, who didn't know what I was talking about. We'll leave them to carry out 'safety' checks (marketing fishing opportunities for anything they can upsell) such as replacing (part worn) full price brake pads at full workshop prices shall we? Why am I so cynical...
 
Bobby-gg said:
I find this a handy reference tool

www.tyresafe.org

Motorhome Tyre Pressure Calculator | TyreSafe

Our motorhome tyre pressure calculator gives you the correct pressures for your motorhome. Check your tyres regularly for your safety.
www.tyresafe.org www.tyresafe.org
Click to expand...
That's a good reference but a little confusing with the footnote:

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.
NEW SEARCH
 
Lenny HB said:
No noticed that (my books at home) but I have the maxi chassis.
Click to expand...
Lenny (different topic) I know you've fitted extra sockets I'd value your input in my new post "Holesaw through perspex splashback"

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Woodgates said:
I recently used the dynamic scale weighbridge at King George Dock in Hull with the following results:

Front 1810. (Plated at 1850)

Rear 1550. (Plated at 2000)

Gross 3360. (Plated at 3500)

This was in holiday trim with 2 adults included (for a week), ie. full fuel tank, full fresh water, full lpg underslung, empty grey waste, empty cassette. We don’t carry bikes or bbq but do have mountain walking gear and then general clothing and food of course! etc.

Contacted Continental Tyres for their recommended tyre pressures

Front 3.5 bar (50psi), Rear 3 bar (45psi)

This made for a really comfortable ride compared with the factory set up of 60psi all round.

Vantage Sol PVC 6m

Derek
Click to expand...

I'm surprised at bigger pressure on front to rear. I'm also surprised how light you are at the rear which is probably a result of the light rear weight. Having said that you do seem to travel light, full water excepted.

What model do you have?
 
Baycott said:
That's a good reference but a little confusing with the footnote:

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.
NEW SEARCH
Click to expand...
Doesn't confuse me, I don't run cp tyre's, but see Tigger-Tim post, #18 for an explanation

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