Fiat Ducato (Swift Select/Spirit 122) - Tyre Pressures

[DartmoorPete]

I've been meaning to do this for ages, but I finally got to a weighbridge today to try and get a more accurate calculation done for my tyre pressures.
This resulted in 1,600kg(F) and 1,260kg(R) in "Winterisation" condition (ie no water, equipment etc on board)
I've made allowance for all the additional weight we'd normally carry (ie Fresh & Heater Water, 2x persons, food/clothing/equipment etc) which I reckon would be no more than 400kg. Splitting this front & rear I end up with adjusted weights of 1,800kg(F) and 1,460kg(R).

Continental supplied me with the table below for the exact tyres (225/75 R16CP) I have on the vehicle.
Applying my (above) adjusted weights to this (and "rounding" upwards a bit) suggests I should be at 3.25bar(47psi) for Fronts and 3.00bar (44psi) for the rears. As I tend to work in PSI, rounding these up to 50psi (F) and 45psi (R) would seem about right.

HOWEVER, the advice from Swift is that tyre pressures should be as per the Fiat Ducato Owners Handbook:- this very clearly says for my exact camper tyre size that the pressure should be 5.5bar(80psi) all round!!??

This seems like a massive anomaly - can anyone tell me if I've missed something..........
Thanks!

 

[JSW]

I've been meaning to do this for ages, but I finally got to a weighbridge today to try and get a more accurate calculation done for my tyre pressures.
This resulted in 1,600kg(F) and 1,260kg(R) in "Winterisation" condition (ie no water, equipment etc on board)
I've made allowance for all the additional weight we'd normally carry (ie Fresh & Heater Water, 2x persons, food/clothing/equipment etc) which I reckon would be no more than 400kg. Splitting this front & rear I end up with adjusted weights of 1,800kg(F) and 1,460kg(R).

Continental supplied me with the table below for the exact tyres (225/75 R16CP) I have on the vehicle.
Applying my (above) adjusted weights to this (and "rounding" upwards a bit) suggests I should be at 3.25bar(47psi) for Fronts and 3.00bar (44psi) for the rears. As I tend to work in PSI, rounding these up to 50psi (F) and 45psi (R) would seem about right.

HOWEVER, the advice from Swift is that tyre pressures should be as per the Fiat Ducato Owners Handbook:- this very clearly says for my exact camper tyre size that the pressure should be 5.5bar(80psi) all round!!??

This seems like a massive anomaly - can anyone tell me if I've missed something..........
Thanks!


View attachment 867139

My Murvi Morello (Fiat Ducato lwb heavy chassis) was supplied new with Continental tyres in 2016 & I have used their recommended pressures (47.1 psi front & rear) with no problems. I've just replaced them because they were 9 years old, there was still a lot of tread left & no apparent perishing after 28,000 miles.

 

[Guigsy]

I've done very similar. Continental non-camper tyres and using their handbook means I can run significantly lower pressures.

Trying to estimate how weight will affect axle loading isn't easy. Every kg you add behind the rear axle will decrease the weight on the front and add more than a kg to the rear. So splitting 50:50 is probably unrealistic.

I assumed I was running the vin plate axle weights. This meant about 50psi front and 55psi rear. This is still very low (the tyres look quite bulged), but I know that I'll not be under the required tyre inflation unless I'm also overloaded...

 

[Vaman]

We too have just come back from the weighbridge. We have loaded the van with everything to the max, including both of us, but excluding food and clothes, we do not carry much of either. With max fuel, water, gas (external) plus all the chairs table ramps etc etc we came out at 1700 on each axle (50:50) or 3420 across both. There was some wet ballast on one end of the public weighbridge (builder merchant) which would account for perhaps 10+ kgs.

It is a Ducato maxi 6.3mtr chassis and the official vehicle label guidelines say 65 front/72 rear. These will rise even at this time of the year by around 7 or 8 psi according to our Tyrepal. Then it is quite hard on the non existent East Sussex roads today.

 

[Just smiffy]

HOWEVER, the advice from Swift is that tyre pressures should be as per the Fiat Ducato Owners Handbook:- this very clearly says for my exact camper tyre size that the pressure should be 5.5bar(80psi) all round!!??

Do swift make tyres…? I’d go with continental…. Just don’t asked continental about your swift made cabinets…

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[Vaman]

I have today contacted Continental Technical via email and got a reply within the hour. Like other they have sent through a chart this is for Van Contact Eco 215/75 E16C 116/114R tyres on our DEvon Aztec XL 21 plate.
The load figures are from a recent weighbridge visit.
Like others the chart does not copy over very easily but a png is below I hope.

....................... Their text below.

Based on the 215/75 R16C 116/114R and providing that the weights given are the maximum axle weight you will be subjecting the tyre to; the inflation pressure guidance is:

Front: 3.5 bar (51 psi) 1700kg

Rear (Single fitment): 3.5 bar (51 psi) 1700kg

That should make our ride a bit more comfortable as we have been using the chassis label as the settings.
HTH
Vaman

 

[Just smiffy]

I have today contacted Continental Technical via email and got a reply within the hour. Like other they have sent through a chart this is for Van Contact Eco 215/75 E16C 116/114R tyres on our DEvon Aztec XL 21 plate.
The load figures are from a recent weighbridge visit.
Like others the chart does not copy over very easily but a png is below I hope.

....................... Their text below.

Based on the 215/75 R16C 116/114R and providing that the weights given are the maximum axle weight you will be subjecting the tyre to; the inflation pressure guidance is:

Front: 3.5 bar (51 psi) 1700kg

Rear (Single fitment): 3.5 bar (51 psi) 1700kg

That should make our ride a bit more comfortable as we have been using the chassis label as the settings.
HTH
Vaman



View attachment 905515

That just goes to show that most people have far too much pressure in their tyres…

 

[Vaman]

That just goes to show that most people have far too much pressure in their tyres…

Yes me included