# Vehicle Weights and Tyre Pressures



## Don_Madge (May 1, 2005)

There's been a couple of threads on one of the other M/H forums on Tyres and Vehicle weights so I thought I would give it an airing on Facts. Some might find it useful.

I suggest you contact your local VOSA office, normally the' re only too pleased to help anyone who genuinely wants to stay within the weight limit for their vehicle. I would advise anyone who wants to weigh their vehicle to load it to the same degree they would when using it under normal conditions before taking it to be weighed, don't be tempted to weigh it empty, unless you weigh every item and are very careful over where you stow it you could quite easily find you're overweight on either an axle or on the gross. 

Don't worry if your vehicle is found to be overweight when you take it to be checkweighed - it's a defence in law to be proceeding to the nearest weighbridge by road to check your weight - but you must return to the place of loading to offload the excess before proceeding on your journey. 

By the way, it's really quite easy to "split" weigh a vehicle on a static plate weighbridge, provided the approach to and exit from the plate is relatively level. Drive your vehicle onto the plate until the rear axle (or in the case of a three axle vehicle, the second axle) is just off the plate - note the weight, this is the first axle weight - drive the vehicle completely onto the plate and note the weight again, this is the gross weight - simple math's, take the first axle from the gross and you have the weight of the second (or second and third) axle(s). You now have the first and second axle weights and the gross weight in a loaded condition. Provided they're within the limits shown on the manufacturers plate you don't have a problem. (And just in case you're wondering - the sum of the first axle weight and second axle weight shown on the plate will always be more than the permitted gross weight shown on the plate, this is to allow for weight distribution.) 

For all interested party's these are the tyre pressures and axle weights for my Timberland LWB Ducato with a MAM/GVW of 3300kg 

Tyres. 
Goodyear Cargo G 26 205/70 R15C 106/104R 

Front axle weight 1680kg (Max allowed 1750kg) 
Rear axle weight 1620kg (Max allowed 1850kg) 
This puts me at 3300kg MAM. 

Front tyre pressure 54psi (3.72bars) 
Rear tyre pressure 62psi (4.27bars) 

At present I've done almost 42,000 miles on this set of tyres and there's still plenty of wear left. 

A part of this post is from a thread on the Motorhome List about a year ago.

Regards

Don


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## vicdicdoc (May 14, 2005)

I'm starting to show a slight wear to the outside edge of the offside rear tyre & wondered if its due to wrong pressure . . [I don't know the 'official' tyre pressure so I usually put it to 4.5bar . . would this be the cause [too low / too high] ??
its on a Fiat long wheelbase Hymer 3500kg


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## 88781 (May 9, 2005)

I think what we need is database of all corellated info on motorhome tyre pressures, an 'at a glance' reference chart for all members to be able to look at and find the correct tyre pressure for any motorhome from hi -top to A class.

Dave 


ps great post Don :wink:


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## vicdicdoc (May 14, 2005)

Good idea Dave - I'm always at a loss as to what pressures


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## sprokit (May 1, 2005)

> I suggest you contact your local VOSA office, normally the' re only too pleased to help anyone who genuinely wants to stay within the weight limit for their vehicle.


Hi Don

Glad to see someone, somewhere actually read and kept my email on this subject - but, please, don't just turn up at a VOSA office, we're not tied to desks all the time, give us a call. Firstly, we can tell you whether we have a weighbridge close at hand, second, we can arrange a time when it's convenient to both parties to weigh the vehicle and thirdly, we may even be able to give you some advice on how to load your vehicle to avoid overloading - well........ maybe, I think mine is running heavy at the moment - and it would be embarrassing to be stopped and reported by my colleagues 

Keith


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## xgx (Oct 14, 2005)

vicdicdoc said:


> I'm starting to show a slight wear to the outside edge of the offside rear tyre & wondered if its due to wrong pressure . . [I don't know the 'official' tyre pressure so I usually put it to 4.5bar . . would this be the cause [too low / too high] ??
> its on a Fiat long wheelbase Hymer 3500kg




As I understand it, over inflation results in wear at the centre of the tread... underinflation causes the wear on the outer edges (note thats both edges)

Most tyre fitting places are usually happy to offer advice... especially if it might mean a bit of business :wink:


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## Don_Madge (May 1, 2005)

sprokit said:


> > I suggest you contact your local VOSA office, normally the' re only too pleased to help anyone who genuinely wants to stay within the weight limit for their vehicle.
> 
> 
> Hi Don
> ...


Hi Keith,

Nice to hears from you again.

Lets hope the 10,000 facts members don't all conntact their local VOSA office for advice.

I think people are more aware these days of the dangers of overloading their motorhome. Seeing the very small payloads on some coachbuilts it's a small wonder more people arn't pulled.

This is a recent post from a Euro Truck Drivers Forum.

" Do you know wht is nice ,it is seeing the police here in Germany pulling the caravan drivers and mobile homes over and doing a complete check which includes on the weighbridge, and checking how they have loaded 
the vehicle(s) ,and YES they are all ways giveing out ticketsto on average 8out of 10 caravanners that they check"

I don't know how true it is but there's no smoke without fire.

Regards

Don


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## davoscar (Feb 28, 2006)

*Probs at weighbridge though!*

I've just been through this exercise of getting our new motorhome weighed in order to check with Michelin (It was delivered with 80 psi all round and the ride was really hard and banged and crashed at every pothole). The problem I had was when I turned up at the weighbridge the operator flatly refused to weigh individual axles - said it was illegal - So I pays me seven quid for a ticket with just the total weight! After reading all about it (on another forum actually) I think 'this is all tosh' so I go back and remonstrate with the lady, she is adamant but finally relents to 'tell' me the individual weights if I drive on again.... what a palaver

Anyway for the record it is a Pioneer Jolliet (Autocruise Starfire) on a Peugeot Boxer 2.2 Hdi with upgraded chassis and air rides

MGW 3700
Front axle 1350
Rear axle 1850

Michelin gave pressures 44 front 59 rear

Since changing and reducing air-rides from 3bar to 2 bar driving is a dream, all the banging and rattling over pot-holes has stopped and much better feel in the steering. Very worthwhile, if frustrating exercise David


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## sprokit (May 1, 2005)

> Lets hope the 10,000 facts members don't all contact their local VOSA office for advice.
> 
> I think people are more aware these days of the dangers of overloading their motorhome. Seeing the very small payloads on some coachbuilts it's a small wonder more people aren't pulled.


Hi again Don

I'd rather they contacted us for advice than go blindly on thinking they were legal when they weren't - and only find this out when they're stopped by either our wonderful Traffic Officers or ourselves - how many know that VOSA now have the power to stop and check your vehicle, for Construction & Use defects (which can include weighing), using our marked vehicles. In case anyone is wondering - the VOSA cars are silver Ford Galaxy vehicles, battenburged in Black and Yellow (Not the big ugly 4 x 4's the HATO's use).

Over the past 3 or 4 years I think I've weighed 12 M/H's - only 3 were not overweight, although the overloads were only in the region of 60 to 150 Kg, usually on the rear axle, the 150 Kg overload is enough to attract a prohibition and possible prosecution. However, this type of overload is normally fairly easy to clear - emptying the fresh water tank and/or the grey water tank and/or moving some of the vehicle's contents around is usually enough to clear the overload. (And as a bonus - none of the owners were prosecuted - a warning letter was considered sufficient, although a record is kept just in case they ever "cross our path" again with the same problem.)

Just to clear up any misunderstandings the members may have - whilst it is a defence in law to be proceeding to a weighbridge to check weigh the vehicle - it must be the nearest weighbridge, by road, (even if it's in the wrong direction to that you want to travel) from the place where the vehicle was loaded, and, if when you checked the weight you found it was overweight, you must return to the place it was loaded to remove the excess weight. So don't go thinking you can tell the officer weighing the vehicle that you're just going to a weighbridge to checkweigh when you're 300 miles from home (where you loaded the vehicle) and having passed many weighbridges since leaving, we just don't accept that.

A lot of checks for roadworthiness are carried out on caravans and M/H's during the summer season - you'd be surprised how many people just don't bother to check their vehicles after a winter layup (there are some who don't use their vehicles/caravans throughout the year - what a waste!!) and are 'surprised' when we tell them the brakes aren't working properly or they have a seized load sensing valve etc.

Anyway, the offer of advice is there for those who want to ask, and if you don't ask, you may just muddle along in blissful ignorance and never have a problem or, on the other hand, find yourself, at worst, paying out lots of hard earned cash and possibly sending your licence away to Swansea for those lovely points to be put on it.

In reply to 'davoscar' - it may be that the particular weighbridge you went to is not authorised by the certifying authority (Trading Standards) for "split weighing". But, providing the approach to and exit from the weighbridge plate is level, although the figures may not be 100% accurate, they are usually close enough to give you a fair idea of whether your axle weights are correct or not - you only have to weigh the first axle and Gross weight to obtain the rear axle weight (simple arithmetic, Gross - 1st axle = 2nd axle). I know of several weighbridges in my area which, although the plate is not authorised for split weighing, the operator, if spoken to "nicely" will weigh the vehicle in this manner.

Now - I really must listen to my own advice and take my vehicle to a weighbridge - although I'll have to get one of my colleagues to sign the weight ticket, it would never do to sign my own ticket - would it :twisted: ??

Take care out there and enjoy.

Keith


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## 98937 (Apr 28, 2006)

*Tyre pressures*

Hi Dave
I had a similar experience when my new Autocruise Wentworth was delivered. It had 80psi all round with nothing in the air ride! The ride was terribly hard. I put 2bar into the air ride and reduced the Michelin tyres to the handbook recommended pressures of, front 48 psi, and rear 58 psi, what a difference it made, we now ride nice and smooth.
John


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## davoscar (Feb 28, 2006)

*Tyre Pressures*

Thanks John... I agree it makes all the difference in the world; makes you wonder how they get out of the factory like that, or is it the dealer doing the PDI David


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## StAubyns (Jun 4, 2006)

Hi

When we collected our new motorhome it came with 80psi all round and the ride was hard to put it mildly.

As yet I have not had the chance to get to our local weighbridge but I did email Michelin and received the following reply. Hope it is of interest.

"The tyre size quoted is able to run at the following axle loads/pressures, when
fitted to a 'single fitment' axle (one tyre only each end of axle):

215/70 R 15CP 109Q 'XC Camping'

Axle weight Pressure
(Kgs) (psi)

Quoted wts: 1750 54 Front
Quoted wts: 1850 57 Rear

+10% front axle:
Should you wish to help the front axle tyres cope more easily with the weight
transfer forward under braking, we suggest that you may increase the front tyre
pressure by 10% above any final calculated 'static' value, providing the maximum
pressure (80 psi) is not exceeded.

Final recommended pressures:

Front: 59 psi
Rear: 57 psi

* Note: The above pressure values are only recommended for the axle weights
stated above.
Have you verified that each axle weight for your vehicle is actually being run
at or below these quoted weights, by visiting a local weighbridge? 

Weighbridge:
We suggest that individual axle weights from weighscale readings are used, in
order to calculate pressure recommendations for each quoted load conditions.
These would be preferred, due to readings being taken in the actual vehicle
'running' condition - that is to say, with all water/fuel/baggage & passengers
etc. onboard - and may result in better comfort if the vehicle is running way
below maximum capacity.

The results of surveys show that too many motorhome users run their vehicle
overladen (read illegal), with little regard for axle weights and subsequent
tyre related problems.

The overall industry, therefore, tries to build-in a safety factor by fitting
specific, strong 'motorhome' tyres, inflated to high pressure, in order to
prevent the drastic consequences of overloading &/or under-inflating the tyres.

The drawback of this safety factor, at the corresponding high pressure, is an
extremely hard ride. The contents of the motorhome may rattle, but the tyres
will cope nicely.



Once again thank you for your interest in Michelin

Yours sincerely
Michelin Tyre Public Limited Company"

regards

Geoff


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