CAB Posted January 13, 2010 Share Posted January 13, 2010 .... something I have been puzzled about for some time. Hypothetical situation - just a mental exercise: My van is plated for a maximum laden weight of 3500Kg. I loaded up for the holidays and found that (with full load, wife, kids ....) it comes in at 3495Kg. However, I still have the bike to put on the installed rack at the back - 25Kg. This will take me over the limit. (^) I've always facied light alloy wheels (and have more money than sense) so I replace the 4 wheels + spare with alloys and low profile tyres. The alloys each weigh 5Kg less than the steels - so the van now weighs 25Kg less. Question: Has my load capacity increased by 25Kg or 5Kg (or even 20Kg)? If I now load up the bike am I now over: The legal maximum all-up weight? The load capacity set by the manufacturer? Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 13, 2010 Share Posted January 13, 2010 The authorities are not interested in the load capacity - similarly they are not interested in the unladen vehicle weight - all that they are concerned with is when you drive onto a weighbridge the total weight of the whole shabang is under the maximum plated weight of 3500kg. Link to comment Share on other sites More sharing options...
bob b Posted January 13, 2010 Share Posted January 13, 2010 Have you thought about a trailer? It would solve a lot of problems. I tow a motorbike trailer and it really causes me no grief at all. The reversing camera shows it clearly, and on a few occasions I've reversed it round a corner just using the camera first (or second) go ! I've taken it to Europe and experienced no problems. Worth considering if your concerned. Link to comment Share on other sites More sharing options...
Guest Tracker Posted January 13, 2010 Share Posted January 13, 2010 Trailers are OK except if, like us, you like exploring off main roads! Having once had to reverse a car and long wheelbase boat trailer several hundred yards up a twisty Devon lane due to a broken down down tractor and trailer I am in no great rush to have to do the same thing with a motorhome pushing a small short wheelbase trailer so as far as we are concerned it all has to go inside or it don't go with us!! Link to comment Share on other sites More sharing options...
bob b Posted January 13, 2010 Share Posted January 13, 2010 I take your point Tracker. When I get to a site, the bike comes off and the motorhome stays there. That said, if CAB can't manage with the payload he's got, then its worth consideration. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 14, 2010 Share Posted January 14, 2010 CAB If you take any sort of 'mechanical' weight-saving measures relating to your motorhome (eg. fit lighter wheels or lighter cab-seats, dispense with the living-area's heating system, chuck away the radiator grille, grind off all the paint, etc.), then your vehicle's potential payload will naturally increase by the amount of weight you've saved. But your motorhome's maximum permitted overall weight as shown on its VIN-plate (in your case 3500kg) won't have been affected, nor will its maximum axle loadings. If your vehicle were (hypothetically) 3495kg fully loaded and you added a 25kg bike, then you'd be 20kg over the 3500kg limit. If you than made 20kg weight savings, then you'd be right on the 3500kg limit. If you made 25kg weight savings, you'd be back to 3495kg and 5kg below the the 3500kg maximum. I honestly can't see why this should puzzle you. Link to comment Share on other sites More sharing options...
messerschmitt owner Posted January 14, 2010 Share Posted January 14, 2010 except, if the bike is on a rack at the back, it'll have an effect on the rear axle weight too disproportionate to its actual weight. We now need to know the length of overhang to work out the force of the bike on the back axle! Should have bought a 4.6 tonner! Link to comment Share on other sites More sharing options...
colin Posted January 14, 2010 Share Posted January 14, 2010 To answer your hypothetical question. I've got a tech data list in front of me, it quotes:- Weights* Mass in running order Essential habitation equipment Max. user payload Max. technical permissible laden mass *own weight and towing weight may differ +/-5% It then goes on to list options and how much weight these add or subtract. So thay haven't given a load capacity, just a guide. This has thrown up another query, in older tech data a weight saving of 10kg is quoted for ali wheels, in the 2010 tech data this is now 1kg, I wonder which is correct? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 14, 2010 Share Posted January 14, 2010 colin - 2010-01-14 12:50 PM This has thrown up another query, in older tech data a weight saving of 10kg is quoted for ali wheels, in the 2010 tech data this is now 1kg, I wonder which is correct? I would have thought the 10kg figure is more likely to be right. I have a 2007 Hymer brochure that quotes a 15kg weight-saving for an optional set of 4 alloy wheels (15" or 16" wheel-diameter and irrespective of the make of base-vehicle). Link to comment Share on other sites More sharing options...
colin Posted January 14, 2010 Share Posted January 14, 2010 Derek Uzzell - 2010-01-14 6:27 PM I would have thought the 10kg figure is more likely to be right. I have a 2007 Hymer brochure that quotes a 15kg weight-saving for an optional set of 4 alloy wheels (15" or 16" wheel-diameter and irrespective of the make of base-vehicle). Yes thinking about it 2.5kg per wheel which is roughly 10% sounds about right. Link to comment Share on other sites More sharing options...
CAB Posted January 14, 2010 Author Share Posted January 14, 2010 OK - it was all hypothetical.. ai suppose the question I was really asking (on the figures I gave) was does "losing" 20Kg on the weight of roadwheels really have any effect on the load capacity? After all there is no equivalent reduction in load on the front and rear suspension? To answer my own question I would think that only an additional 5Kg of load can be carried (the saving on the spare wheel) to keep within the Manufacturer's suspension loading limits (OK - I know there will be a good safety margin built in), but the full 25Kg as far as the regulatory authority is concerned as they would only be interested in the overall weight. Now shoot me down! Clive Link to comment Share on other sites More sharing options...
Mel B Posted January 14, 2010 Share Posted January 14, 2010 If the manufacturer offered the change to lighter alloy wheels for the vehicle then I would expect the existing suspension to be able to actually 'carry' the extra weight legally that the lighter wheels would then allow to be carried to still be within the overall payload, if not, then the payload would need to be downrated at the same time the alloy wheels were fitted to be 'legal'. If it was that 'crucial' I'm sure they'd only allow owners to get away with a reduced official payload of 3400 instead of 3500 normally to cover themselves! 8-) Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 15, 2010 Share Posted January 15, 2010 A motorhome's VIN-plate will carry maximum authorised weight-limit data relating to the vehicle's overall weight, its overall 'train' (towing) weight and its axle-load weights. All of these figures are fixed and finite and, if any (that's ANY) of them are exceeded, the vehicle becomes illegal and its driver can be prosecuted. A motorhome, after its conversion has been completed, will (obviously) have a weight. How the converter expresses that weight tends to vary. Taking Colin's example, the converter may provide a "mass in running order" figure and an "essential habitation equipment" figure. The total of these two figures subtracted from the overall-weight figure on the motorhome's VIN-plate would provide the "maximum user payload". However, unlike the VIN-plate data, the motorhome's post-conversion weight is not fixed, as the vehicle's owner may choose to add accessories like an awning, tow-bar, cycle-rack, etc. all of which will simultaneously increase the motorhome's weight and reduce its 'user payload'. Conversely, if the owner alters the motorhome's specification in a weight-saving way (and replacing steel wheels with lighter alloy ones is a classic case), then the vehicle's 'user payload' will increase by the amount of weight saved. If you've fitted 4 alloy wheels, each 5kg lighter than the original steel ones, then you've 'saved' 20kg and your motorhome's payload will have risen by 20kg from whatever it was before you swapped the wheels. If you then exploit that increased payload so that other weight-limit maxima are exceeded (eg. by a rear-mounted bike causing a rear-axle to be overloaded), then that's nothing directly to do with the user-payload figure. As I said earlier, the user-payload figure results from a simple arithmetic subtraction - it's not specifically 'chosen' by the motorhome converter. You don't up-rate or down-rate the payload; you up-rate or down-rate the motorhome's overall weight and the payload alters upwards or downwards accordingly. If you scan through the Panel Van Conversions (PVCs) section of MMM's January 2010 Buyers' Guide (pages 221 and 223), you'll see that, for PVCs with a 3500kg maximum overall weight, the quoted payload can vary from below 400kg to above 1000kg. It's not unreasonable for motorhome converters to expect purchasers of their products to behave sensibly, but, if Dopey Dan buys (say) an Autocruise Tempo PVC and subsequently squanders all its 600kg payload by (hypothetically) carrying a massive motorbike on a rear-mounted rack, then there's nothing that the converter can do to guard against Dan's folly and its inevitable rear-axle overloading result. CAB's inquiry is more complex than it may appear at first sight, as it involves 'sprung' and 'un-sprung' weight. Road wheels are in the un-sprung weight category, so fitting alloy wheels that are lighter by 20kg than the steel originals will increase a motorhome's user-payload by 20kg, but it won't reduce the loads being placed on the vehicle's axles as these fall into the 'sprung weight' category. If a motorhome's axle is at its absolute maximum weight limit, then this situation won't be improved by saving un-sprung weight. To reduce 'mechanical' sprung weight, and thus reduce an axle loading, you'd need to make 'above the axles' weight savings (eg. fitting lighter cab-seats, dispensing with the living-area's heating system or its oven, chucking away the radiator grille, etc.) Link to comment Share on other sites More sharing options...
Fionablueinky Posted January 20, 2010 Share Posted January 20, 2010 Hi Iv'e found this thread very interesting, and it reminded me of when we first got our coachbuilt van, we loaded the van up with all our gear for me, my husband and our son for a 6 week trip to france, all the bikes were on, a full fuel tank and half a tank of water, food and beer as we where going away locally, only my son was missing when we took the van to the weighbridge, and it turned out we where overweight by about 60kg, obviously we had to add my sons weight to that as well :$ So I had to go through the van with a fine toothcome, its amazing what you can get rid off when you have to do it, every single glass bottle in the van went changed everything to plastic, even the optrex, the olive oil and the spices. pans, plates, cups, cutlery was parred down , clothes, only books we could all read where allowed, one ipod, one pair of trainer and sandles each, shared toiletries in smaller bottles, smaller towels, etc...I was like a women possessed!!! anyway the upshot was took the van to the weighbridge again with my son as well and we had 40kg spare. So if you are struggling for payload take a look at what your carrying it may be possible to change it about or get rid of some, we even had enough to bring some belgium beer back with us :-D Link to comment Share on other sites More sharing options...
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