Unsafe weight on rear axle - tyre pressure recommendations?

[Chris63]

Good afternoon Funsters,
I have been to the weighbridge and got both axles independently weighed
Full tank of diesel and also water
The usual kit , nothing OTT
Front axle1660 kg , rear 2400 kg
The web site says front 47 psi , rear 80 psi
The website also said that the rear axle was close to an unsafe weight
Any thoughts
Best wishes
Totthedog

 

[Guigsy]

Hi Pausim
My van is a 4500 kg Autotrail Dakota
Regards
Totthedog

In which case, the plate under the bonnet must have been superseded by another one.

 

[Pausim]

Hi Pausim
My van is a 4500 kg Autotrail Dakota
Regards
Totthedog

Where does the 4500kg come from? Just adding the axle weights together does not mean it has been registered at that weight and the plate under the bonnet only shows 3500kg. How much road tax are you paying? This would also indicate whether you are allowed over 3500kg.

 

[Chris63]

Where does the 4500kg come from? Just adding the axle weights together does not mean it has been registered at that weight and the plate under the bonnet only shows 3500kg. How much road tax are you paying? This would also indicate whether you are allowed over 3500kg.

Good afternoon,
The V5 document states revenue weight 4005 kg
Totthedog1

 

[Guigsy]

Good afternoon,
The V5 document states revenue weight 4005 kg
Totthedog1

Somewhere on the vehicle you should find another Vin plate that matches that 4005kg weight. I suspect it'll have the same 2100kg, 2400kg ratings on the front and rear axles.

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[Pausim]

Good afternoon,
The V5 document states revenue weight 4005 kg
Totthedog1

That leaves a much more manageable 55kg to lose from your weight though the rear axle loading leaves nothing to spare.

 

[Tigger-Tim]

Somewhere on the vehicle you should find another Vin plate that matches that 4005kg weight. I suspect it'll have the same 2100kg, 2400kg ratings on the front and rear axles.

It might not look like a VIN plate. THis one is a bit unusual!

 

[georgio]

On ten ply tyres I would definitely run at 80 psi on that weight, the front I would put in about 60 psi. The heat build up running on low pressure with that weight would be huge.

 

[funflair]

On ten ply tyres I would definitely run at 80 psi on that weight, the front I would put in about 60 psi. The heat build up running on low pressure with that weight would be huge.

I reckon 10 ply would be 121 rated, Continentals chart says 69psi at 2500kg for the size 225 75 16.

 

[John Mee]

Hi, I am a newbie and learning. Can someone explain, if the van has been uprated, how do the axle ratings stay the same? Cheers John.

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[funflair]

Hi, I am a newbie and learning. Can someone explain, if the van has been uprated, how do the axle ratings stay the same? Cheers John.

Each axle has it's own rating but the two don't always add up to exactly the Maximum allowed MAM, for example you might have 5t on the rear and 2t on the front but a MAM of 6.5t you would not be allowed to overload either axle, you could then uprate suspension wheels tyres etc to go to 7t MAM but still keep the original axle loadings.

 

[John Mee]

Each axle has it's own rating but the two don't always add up to exactly the Maximum allowed MAM, for example you might have 5t on the rear and 2t on the front but a MAM of 6.5t you would not be allowed to overload either axle, you could then uprate suspension wheels tyres etc to go to 7t MAM but still keep the original axle loadings.

So, if I uprated my van from 3500kg to gain the tax advantage I wouldn't necessarily be able to carry any extra weight?

I just went and looked at my plate it says 3500kg 5500kg 1 1850kg 2 2000kg

 

[Speve]

So, if I uprated my van from 3500kg to gain the tax advantage I wouldn't necessarily be able to carry any extra weight?

You would be be able to carry extra weight if your vehicle permits as explained by others usually your axle weights added together are higher than you are allowed to carry which gives you the opportunity to balance your loads over both axles without exceeding your GVW
if you uplate you usually need larger tyres and perhaps air assist on the rear which then gives you more GVW allowing you to load up to the max on your axles without being over GVW.
when you do this you will get a new plate to put on you van

 

[Lenny HB]

So, if I uprated my van from 3500kg to gain the tax advantage I wouldn't necessarily be able to carry any extra weight?

You often find that if you uprate to 3850kg you will only gain what extra you can load on the rear axle as normally not much you can move forward.
I uprated our last van of the 3500kg increase I could only use 150kg as that put the rear axle at it's max.

Although you can increase the rear axle load by changing the tyres if 15" wheels (16" normally OK) and fitting rear air assist suspension then you can go from 2000kg to 2240kg on the rear.
Those figures are for a Fiat chassis.

 

[John Mee]

Thank you. I didn't plan to uprate just yet and now I think I'll try to stick at 3500kg!

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[Lenny HB]

On ten ply tyres I would definitely run at 80 psi on that weight, the front I would put in about 60 psi. The heat build up running on low pressure with that weight would be huge.

Van tyres are 10 ply Camping tyres 8 ply.

Assuming the tyres are 225/75/16 with a load rating of 118 it would be 74psi for van tyres and 75psi with a load rating of 122.

 

[Lenny HB]

You often find that if you uprate to 3850kg you will only gain what extra you can load on the rear axle as normally not much you can move forward.
I uprated our last van of the 3500kg increase I could only use 150kg as that put the rear axle at it's max.

Although you can increase the rear axle load by changing the tyres if 15" wheels (16" normally OK) and fitting rear air assist suspension then you can go from 2000kg to 2240kg on the rear.
Those figures are for a Fiat chassis.

I obviously meant 350kg.

 

[Don Campbell]

I have Toyo tyres I emailed Toyo they came back with the pressures in ½ hour.
Front 1930kg 56 psi, Rear 2300kg 69psi.

That makes total sense. Some of the tyre pressures quoted for motorhomes are way over the top and lead to a very uncomfortable ride.

 

[Orion]

Although you can increase the rear axle load by changing the tyres if 15" wheels (16" normally OK) and fitting rear air assist suspension then you can go from 2000kg to 2240kg on the rear.
Those figures are for a Fiat chassis.

Sometimes a bit more. I can go to 2400kg rear axle (from 2000kg) on our Fiat base Adria Compact as I’ve fitted Dunlop air. Already have 225/75R16 CP tyres and the 1250kg rated alloys from the factory - looking at 4250kg total.

 

[Lenny HB]

Sometimes a bit more. I can go to 2400kg rear axle (from 2000kg) on our Fiat base Adria Compact as I’ve fitted Dunlop air. Already have 225/75R16 CP tyres and the 1250kg rated alloys from the factory - looking at 4250kg total.

I take it's not an Al-Ko AMC chassis.

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[Orion]

I take it's not an Al-Ko AMC chassis.

Correct.

 

[VXman]

Good afternoon Funsters, The weigh bridge said Front axle 1660kg ,the rear 2400kg.

How was the front and rear weighed? Did the wight bridge have proper separate front and rear scales or was it a case of front wheels on - weigh and then back wheels on - weigh. The 2nd method is not very accurate.

 

[bigtwin]

The 2nd method is not very accurate.

The 2nd method is also not necessarily inaccurate.

Which it is depends on the geometry/topography of individual weigh bridges.

Ian

 

[MichaelT]

My van is 4.5 tons
The website is Tyresafe
Tyres are Davanti 225/75 r16
The plate says 79.5 psi
Regards
Totthedog

What does the weight plate say the axles max load are?

 

[Chris63]

Good afternoon Funsters,
I have been to the weighbridge and got both axles independently weighed
Full tank of diesel and also water
The usual kit , nothing OTT
Front axle1660 kg , rear 2400 kg
The web site says front 47 psi , rear 80 psi
The website also said that the rear axle was close to an unsafe weight
Any thoughts
Best wishes
Totthedog

Good morning Funsters,
What started off with trying to find the correct tyre pressures has escalated into van safety in particular the weight on the back axle which is close to the safety limit, the front is well within the limit. My van has a French bed with most storage on the right hand side rear. To clarify slightly , I do not carry anything out of the ordinary, the water heater is there which does not leave a lot of room for sundries.The solar panel was factory fitted , I usually have the silver screen in the shower but I don't use it during the Summer. I very rarely travel with a full water tank. Consequently I could look at air suspension and possibly fitting a better tyre but mainly it would be to distribute the weight more logically. In a more jocular moment I still don't know the correct tyre pressures . Thanks again for all of the replies , Ive learned a couple of important facts.,
Regards and best wishes Totthedog

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[dawsey]

Nah just a design feature of Camping tyres to give a very stiff sidewall for longer periods of standing in storage. If you use your van regularly then any correct size/load van tyres will do

It is not to do with standing for long periods. The CP tyres are a much stronger construction, designed to run at high pressure to improve handling by reducing body roll, being more resistant to cornering load transfer and static and dynamic overload which are all tendencies of heavily loaded too heavy motorhomes with large over hangs. They improve handling and are safer tyres for the consistently highly loaded campers, that’s why they are recommended.

The compromise is that the ride can be harsher, but even this can be sorted by upgrading the vehicle suspension.

 

[BouncyBoatFolk]

Good morning Funsters,
What started off with trying to find the correct tyre pressures has escalated into van safety in particular the weight on the back axle which is close to the safety limit, the front is well within the limit. My van has a French bed with most storage on the right hand side rear. To clarify slightly , I do not carry anything out of the ordinary, the water heater is there which does not leave a lot of room for sundries.The solar panel was factory fitted , I usually have the silver screen in the shower but I don't use it during the Summer. I very rarely travel with a full water tank. Consequently I could look at air suspension and possibly fitting a better tyre but mainly it would be to distribute the weight more logically. In a more jocular moment I still don't know the correct tyre pressures . Thanks again for all of the replies , Ive learned a couple of important facts.,
Regards and best wishes Totthedog

Just to add another dimension to your list, you can probably fit Sumo "Air Springs" to your van , [ https://www.google.com/url?sa=t&rct...usg=AOvVaw0vu7UJ8H9kr1m0gnFoMcao&opi=89978449].
They are almost a fit and forget option, but have no adjustment, on the fly or otherwise. If you do find you're in need of a back axle uprate to give you some payload flexibility ,[ C1 LICENCE PERMITTING] , I found
"Van Weight Engineering" the most approachable, and cost effective, plenty of others have also used them on here.
Mike.

 

[charliesgrandad]

On Tyresafe website it asks if it is a single or twin rear axle but doesn't say if you enter the weight of 1 axle or the combination of both axles

 

[dunnah01]

It is not to do with standing for long periods. The CP tyres are a much stronger construction, designed to run at high pressure to improve handling by reducing body roll, being more resistant to cornering load transfer and static and dynamic overload which are all tendencies of heavily loaded too heavy motorhomes with large over hangs. They improve handling and are safer tyres for the consistently highly loaded campers, that’s why they are recommended.

The compromise is that the ride can be harsher, but even this can be sorted by upgrading the vehicle suspension.

I think that's what the load rating does

 

[Apacheman]

I have the Michelin Agilis 225/75 R16 Q116 CP tyres. These are no longer manufactured and they have moved to the Crossclimate with a completely different tread. I do have a never used one on my spare and have been trying to source another to make a pair without much luck. Michelin info on the tyres states they were specifically designed for Motorhome’s that stand unused for long periods. Info on their other tyres would suggest that is the only advantage of a CP marked tyre. Because of that they were £40-50 more expensive than the Michelin Agilis 121 rated non CP marked tyres which are more than capable of doing the job and still available, but might perish more quickly if stood for long periods?? Or are we just being conned into buying the more expensive CP marked as good practice is to change them every 5 years anyway.

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[MichaelT]

I have the Michelin Agilis 225/75 R16 Q116 CP tyres. These are no longer manufactured and they have moved to the Crossclimate with a completely different tread. I do have a never used one on my spare and have been trying to source another to make a pair without much luck. Michelin info on the tyres states they were specifically designed for Motorhome’s that stand unused for long periods. Info on their other tyres would suggest that is the only advantage of a CP marked tyre. Because of that they were £40-50 more expensive than the Michelin Agilis 121 rated non CP marked tyres which are more than capable of doing the job and still available, but might perish more quickly if stood for long periods?? Or are we just being conned into buying the more expensive CP marked as good practice is to change them every 5 years anyway.

Most motorhome stand for long periods and are always fully laden, even when you go on holiday most days you may drive for an hour or 2 then it's stood fully loaded for the other 22 hours.