We have a Ducato Mulivan 150 van conversion with 225/75 R16 Michelin X Green Eco light truck tyres The imprinted Max Speed and Cold Pressure on the tyre wall is stated as116km/h at 80 psi.... The Fiat plaque states recommended 450 kPa front and 550 kPa back full load.
The van is bouncing and bumping at these pressures and NOT handling very well... Can somebody recommend legal pressures for a 4,100kg van with the above tyre, please?
copy of my post to the thread re van tyre pressures on Techie forum. may give you somewhere to start for setting yours.
"Our van is a tandem axle, weighing 2750 kg fully loaded, so based on that, the AVERAGE load on each tyre is 690 kg near enough (I know not exactly and this takes NO account of tow ball load, but gives a good start point)
Our tyres on the van show Maximum Load per tyre to be 925 kg at 44 PSI. They are 235/75R 15 AT tyres.
Thus our vans weight is 690/925 as a ratio/%age of maximum load, or 74.6% (near enough to 75%)
Thus I started at 75% of 44 psi, or 33 psi.
I run the tyres at 36 psi, and have found this to be a good pressure during our trips, but do drop a little on dirt, to around the 30 psi. This has been fine over the 30000 kms we have towed the van, and over that period we have had no problems with tyres. I used the same process on our previous van, and towed that some 25000 kms without incident."
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Regards Ian
Chaos, mayhem, confusion. Good my job here is done
Go to a tyre reseller they will be the best advice you can get and they won't mind giving that advice either they have the experience to advise.
For mine a little 4-5 psi is much better that 4-5 psi under tyre runs cooler
Not saying advice here is not good but it's one persons experience the tyre bloke has experiance with hundreds of customers
Here on the farm people with the radial tractor tyres are told ( by tractor dealers ) to run them at 5-6 psi for max traction which is all very good if you are prepared to buy a new set of 8 tyres every 1800 to 2000 hours at around $2000 to $3000 per tyre but if you want them to last 4000 plus hours blow them up to 18 - 20 psi ( advice from tyre reseller ) he has seen it too often farmers complaining that there tyres are stuffed too soon
Woody
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When the power of Love becomes greater than the love of power the World will see peace ! 24ft Trailblazer 5th wheeler n 05 Patrol ute and Black Series Dominator camper trailer ( for the rough stuff)
Ian is correct in his reply using the percentage system. As a further check you can use the 5psi system as a further check. If your tyres are at the correct pressure when cold they should increase by about 5psi after running for a bout an hour. If the go higher than 5psi then your cold pressure is to low and if they are under the 5psi then the cold pressure is to high. Please remember this just a GUIDE.
Thank You all for your input... Have to do some more calculations....
We just had the motor home on a weigh bridge yesterday afternoon and it appears to be only about 3,800 kg full load...
Our motorhomes rear tyres especially are recommended to run 90 Lb . On out back roads the harshness through cabin, body is increadable .. I found one squeak at microwave which drove me CRAZZY ( Crazier ?) until Mrs put a little plastic packing in cabinet . I rang Michelin They just said the recommended pressure are 90 to 100 lb ., I lowered tyres to 45 inside /50 lb outside . Then checked tyre temps after 10 klrs . In 38* ambient 100 Kph . I could easy touch the tread . The ride, harshness has much much improved !! Keep in mind before that I replaced the Bilstien shocks !! $$$ ..Made little difference .. Simple things often work the best !! Seems tyre pressures are set to max load, speed etc .. The front tyres I lowered to 70lb ..
-- Edited by Aus-Kiwi on Wednesday 4th of January 2017 12:00:19 PM
-- Edited by Aus-Kiwi on Wednesday 4th of January 2017 12:01:47 PM
Do not over inflate the pressure which is stamped on your tyre
I have a 2006 Fiat Ducato motorhome AGG of vehicle is 3850 Kg, and I am slightly over/under this weight, depending on fuel/water load
Tyres are Michelin Agilis light truck tyres 215 75 R16 on rear max pressure 65 PSI, I run them at 65 PSI and they look as though they could do with a bit more pressure 225 75 R16 on front 80 PSI max, I run them at 75 PSI, they also look as though they can do with a bit more pressure Running at these pressures, I have no bounce
As a side note the recommended tyres for my vehicle are 215 75 R16 Michelin Camping type tyres Camping tyres have a stiffer side wall, as RV's are noted for being laid up for many weeks/months at a time I was unable to purchase campervan type tyres in Australia
Higher tyre pressure will give better fuel consumption but a bumpy ride Slightly lower pressure than recommended will give a nicer ride, but you will use more fuel
I shall let the experts explain about lack of grip, on under and over inflated tyres, which does not affect me, as I drive to the conditions, as I see/find them
Yes and tyres where possibly 22" payload was way over 6 ton loaded . Also ride or chassis harmonics don't matter too much.
Bigger dia, higher profile tyres help !!
Firstly, you cannot compare tractor tyres or big truck tyres to those on a car, van or caravan - they are different construction and built for different duties.
Secondly, you cannot just inflate to either what's on the vehicle placard (as you may well have a different style of tyre fitted) or what is stated on the tyre as a maximum for maximum load.
As already mentioned here, you need to read what's on the tyre, then proportion it to the actual load on EACH tyre. At the very least, weigh each axle of your van separately, while loaded, so you know what each tyre is supporting, then proportion that out to the stampings on the tyres fitted.
If your van is already bouncing around, I have little doubt that you are over inflated. Doing the calc's above will verify that and show you what pressures you should be running.
The 4 psi rule is also somewhat outdated due to tyre construction changes over time. Certainly with heavier 4WD tyres (A/T, M/T LT tyres) it is not unusual for the pressures to rise some 6 to 8 psi at proper cold inflation pressures. Which reminds me... all pressures quoted and calculated are cold inflation pressures, so those pressures will of course rise as the tyres warm up..
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Cheers, Gerry Lexus LX470 2012 Traveller Sensation Pinnacle 21' Member VKS737 - mobile 3535
