Tyre Pressures

I think 80 psi on the rear is common on a lot motorhomes but 80 psi on the front seems a bit OTT. Are the recommended PSI's to use not the  on the door column of the cab?

David

Unfortunately not. The sticker says refer to the vehicle handbook, this states 80psi front and back.

This is of course 11psi above the tyre manufacturer's maximum, and possibly dangerous, as it will go higher when the tyre is hot

Before you change anything I think you would have to weigh the motorhome to establish axle weights and from there you could work out more accurately what the pressures should be. Interesting you say the Fiat handbook, is there not a separate Swift handbook for the Bessacarr? Perhaps contacting Swift, either direct or via the Swift Talk forum might provide more information.

David

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I would agree with DD's advice above about weighbridge and contacting continental who apparently are very helpful.

I didn't bother myself however. When I noticed that the recommended pressures were higher than Continentals advised max for my tyres, I dropped them all to below that figure. It wasn't very scientific, but on a trial basis, I adjusted the pressures on shorter journeys on the basis that if it felt right and looked right they shouldn't be far out. I have now used 60 psi front and 65 psi rear for over 2 years. The ride is ok and tyre wear is even across the width of the tyre.

I also noticed this year, with the hotter weather, that the pressures went up in the heat by 5-10 psi and needed adjusting.

The problem with later model MH's is the preset pressure monitors. Drop the pressures to a realistic level and you get nagged incessantly with dashboard warnings.

A couple of points :-

Accurately weighing each axle in touring trim and getting manufacturers advice is the best approach. In my direct experience Continental are very helpful and quick to provide pressure advice about their products but some other manufacturers apparently give a default answer of 80psi rear perhaps for legal reasons.

Tyre pressures are given for the tyre when cold so if the tyre when cold is inflated to the correct pressure adjusting (reducing) the pressure because the tyre is hot is not normally appropriate although of course if the tyre is hot (overheating) for another reason e.g.  deflation from a slow puncture/valve problem that a different matter. 

I have e-mailed Continental, giving them the details from the VIN Plate, which gives a max front axle weight of 1850kg, and 2000kg for the rear axle, making a max gross weight of 3850kg.

Of course the max permitted gross weight for the motorhome is 3500kg, so some 350kg lighter than the VIN Plate maximums.

Having had another look at the info on the tyre wall, I see that 5.5Bar is the absolute maximum cold tyre pressure for these tyres, which means that Fiat/ Bessacarr (Swift), recommend running them at the limit, which can't be good.

Certainly with 80psi in the front, the steering is far too light, and twitchy.

Driving on even the slightest HGV created ruts, the requires constant correction.

Earlier in the thread I posted :

I also noticed this year, with the hotter weather, that the pressures went up in the heat by 5-10 psi and needed adjusting.

Just in case anyone has misunderstood that comment, I was referring to the unusually high ambient temperatures we have had this year rather than the pressures increasing due to tyres getting warmer in use.

I checked the pressures when the temperature outside was about 15 deg C in the spring and they were spot on. Without moving the van at all, and in full sun with an ambient temperature of 28 deg C all four had all gone up by 5 to 10 psi just by sitting there in the hot sun. Recently, now the heatwave has gone, and again with no movement, the pressures have dropped again and I've just put a little more back in...

Our maximum recommended tyre pressures were 80 PSI over all four wheels. We always carry an "RAC Ring 900 tyre inflator" which allows for accurate pressure checking and rapid inflation/deflation when required..  Would not be without it. 

K