"The Natural Philosopher" wrote in message
...
..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.

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,