update to poor fuel consumption on Camper FYI

[The Natural Philosopher]

..you may remember I asked about this with reference to an Elddis camper built on a peugeot 2 liter boxer chassis.

Having more or less eliminated the engine system as it showed up well in CO2 tests though 4 garages failed to actually be able to access the EMS using half a dozen different diagnostic boxes and about 50 different possible settings..teh final garage pushed teh tyres from 40 psi to

52ish..this seemed to make a slight improvement so I banged them up to 57/62 on our recent trip, and that does seem to have got the consumption up from 20mpg to maybe 23-24mpg..I will go the full monty of 65 psi all round next time I have access to an airline..

I think the problem arises because the actual chassis has tyre pressures inside the drivers door opening,but these relate to the unloaded van, not the 3.5tonne conversion. In short anyone else reading this who has a camper on a van chassis is well advised to inflate the tyres to the absolute maximum - typically 65psi cold, or even more if you dare, and ignore the safety warnings..in fact anecdotal evidence of tyre failures suggests that hot motorway cruises with underinflated tyres are far more likely to blow them.

My tyres were remarked on by the MOT people as starting to perish and delaminate round the tread to sidewall interface..another typical result of habitual underinflation.

Given that the government in its infinite wisdom (TM), classes this as a commercial vehicle, and therefore not subject to quite such swingeing road tax, the improvement is enough for me to now consider it if not as daily transport, at least as a viable second vehicle whenever I have a largeish load to carry or can be assured of sensible parking at the far end.

Costwise its similar to the old Defender that it replaces, and has the added advantage that you are never stuck for a place to relieve yourself on a long trip..;-)

[gazz]

the sticker on the door of the van should give tyre pressures for the van empty and loaded, mine does,

but it's no use assuming it weighs 3.5 tons, get down a weigh bridge and find out exactly what it weighs, go when they are not busy and get the individual axle weights,

then e-mail the company that makes the tyres you have on the van, tell them it's a motorhome, and the axle and total weights as well asthe exact tyre size and model,

they will reply with suggested pressures for those circumstnaces,

i run goodyear cargo tyres on my motorhome (iveco turbodaily based, weighs

4.2 tons, 1650 kilos front, rest on the back axle) goodyear told me i'm best running 3.5 bar front and 4 bar rear, i have twin rear wheels hence such a low rear pressure for a heavy van as the weights spread out over 4 tyres at the back.

yes underinflated tyres are more likely to blow, but over inflated tyres give a hell of a bumpy ride in a motorhome, in bad cases causing the overhead lockers to part with the walls, but in bad cases the rock hard tyres are more likely to skid under very hard braking, and one of the first things the vehicle inspectors do after a bad accident is check tyre pressures.

The average motorhome gets about 25mpg, aerodynamics play a lot in this, especialy if it's a coachbuilt with a standard overhanging luton, my motorhome got about 27mpg when it was a standard panel van before the body was built on it, it was totaly empty then as well, now with the coachbuilt body, all the luxuaries i put in it taking the weight to 4.2 tons in running order (i.e. 140 litres of diesel in the tanks, 150 litres of water, 90 of gas, 70 of red diesel, full fridge, freezer and larder, all our clothes etc) we now get around 24mpg, which for a 7 meter long coachbuilt isnt too bad,

[The Natural Philosopher]

I prefer to look at the manufacturers website where it states that it weighs 3.5 tonnes. Or at least the later version does. They give no clue as to tyre pressures though.

Or just go by feel. It certainly weighs more than my 2 ton Defender used to, but feels similar to that loaded up with a tonne of bricks and a few people..

Didn't need to do that. The last garage I went top had a chart for the tyre versus various weights..

Anyway Elddis recommend pressures which are totally in conflict with the actual weight of a standard loaded vehicle. At the very best their pressure recommendations apply to vehicles that are totally empty - i.e. kerb weight. Typically thats about 2.8 tonnes..but by the time you are ready to roll, the thing is over 3..

somewhat similar then.

I find that the suspension actually works on most vehicles..

I dont do hard braking either. I am not really confident that the brakes it has are up to stopping 3.5 tonnes that quickly. Certainly locking the front brakes would be an interesting exercise that I doubt its capable of. i wish I could put brakes the size of my old XKR brakes in it...they really did stop 2 tins of jaguar in a hurry..

exactly. I was getting sub 20mpg. Ive rented homes before and a diesel generally does 25-27mpg. This petrol now seems to be somewhere in the

23-25mpg area.

aerodynamics play a lot in this,

Indeed.

[Dave Liquorice]

Not the first time that recommended pressures are wrong. Best way is to check pressures fairly regulary and keep an eye on tyre wear. Wear along both the edges and not the center of the tread too low, wear in the center and not the edges too high. Wear on one edge only bad alignment shows up most on the fronts but the rears can be miss-aligned as well. Wear in patches across the tread faulty shocks or brakes.

[The Natural Philosopher]

When you buy a second hand camper that has done a mere 23000 miles in over ten years..its hard to tell anything about wear.

A couple more factoids have come to light: a recommendation to change tyres every 5 years no matter what..and anecdotes of delaminating underinflated tyres at high temperatures..

Anyway I think this machine is up for new tyres and wheel bearings shortly. 3 tons plus is hard on a chassis designed for an executive saloon..

[Dave Liquorice]

Sort of, it would still show if the previous owner habitually over or under inflated the tyres and if the shock/brakes where knackered. I'd do the basic check round of lights, pressures, fluids etc after taking delivery of a new to me vehicle anyaway.

I've seen that as well I think comes tyre manufactureres and fears about UV degenerating the rubber with a good dollop of nanny state. Certainly look at them for signs of "perishing" and it might be wise for such a heavy vehicle to be raised on to axle stands when stood for months on end.

[Steve Firth]

No it doesn't. It states that the GVW is 3.5 tonnes, which is not the same thing.

[The Natural Philosopher]

Oh, that was done by the dealer..MOT and so on..

well I am more or less using it as - well fortnightly transport..since the road tax situation makes it expensive to keep unused/seldom used vehicles on the road, its getting used as a second car..insurance is cheap too.

Tyres ARE bad,espcecially the rears..cracking and splitting at the tread/sidewall interface.

Will definitely get a new pair soon..whats good? don't need long life, so much as low rolling resistance :-) Think its 195/70 15s...

[Dave Liquorice]

My basic distrust of so called "professionals" would still have me checking the vehical over.

Surprised it got through an MOT like that. But looking at the MOT manual it makes no mention of "perishing" just "cuts, lumps, bulges, tears, exposure of the ply or cord, or tread separation".

Pressure is not checked either but:

under-inflation Note: Under-inflation of a tyre is not in itself a reason for rejection. However, a brake test might be inadvisable, because of possible damage, or a headlight test might be affected, if the under-inflation is affecting alignment

Will definitely get a new pair soon..whats good?

Define "good", one of the "green" tyres will give you the low rolling resistance but they cost more. If you aren't doing a really high mileage then your probably better of getting a bog standard tyre as the small change in mpg will take a long time to recoup the extra tyre cost.

[gazz]

thats what i was getting at with the weighbridge thing, thing is most motorhome owners are scared of them as it would most likely show their vehicle is overloaded,

half the motorhomes built nowadays seem to weigh around 3.3 tons empty, add your clothes, a bit of water in the tank, some food and there's no weight allowance left over for the driver, half of the problem is motorhomes built on the al-ko chassis would have origionaly been designed for it being rated at 3.8 tons, but they get de-rated to 3.5 tons to sell more.... limitations of licences, higher speeds on dual caridgeways, cheaper road tax for the european sold models etc.

One of the reasons i chose the iveco as my base vehicle when building my motorhome was it uses the same chassis, engine and drive train on the 6 ton version as it does on the 2.8 tonner, everything is heavy duty... and hence expensive, rear wheel bearings are 100 quid each, discs are about 60 quid each, shockers are 50 quid each and almost take 2 people to compress and extend then a few times to de-airate them before fitting.

[The Natural Philosopher]

well it is costing about 25p per mile fuel, so 10% would be 2.5p per mile.

If two better tyres cost a tenner more each, that's break even at £20/2.5p miles or 800 miles. Not a lot in say the 5 years of the tyres life..

I did that much last week..

[The Natural Philosopher]

From what I can glean its about 2.9 unloaded..only about 600kg of s**te allowed.

2 people and 2 dogs is at leasts 100kg of that..then theres a bolt on boot full of stuff..there must be maybe another 50-100kg of generalised camping stuff...so its at least 3 tons ..

In the end I am not that concerned about what it exactly weighs: the only downside of overhard tyres - and that on the charts would never be more than 10% over at max pressure - is the harder ride and less traction on the loose or under braking.

The benefits - tyres that don't prematurely wear out from flexure, and better fuel consumption, is a worthwile return on the slight risk.

[dennis]

If you look at the weather you will say sod being green and fit some nice wet weather tyres. Green has no place if it endangers people and having stiff non sticky tyres is not a good idea in the UK.