Technical Changing the factory steel wheels for Alloy wheels; pressures ?

[Gessie]

Hi, I have just changed my 2014 Ducato Campervan 15" steel wheels for 16"alloy wheels with the same brand tyres that it came with, Bridgestone Duravis.
The tyre pressures for the steels were 65psi front and 55psi rear. The Wheel company say that they have put 45psi in all 4 tyres as van alloywheels run on a lower pressure.
Searching online says there is no difference and to keep the Fiat recommended pressures. Not sure what is correct . The Company are a very popular good alloy wheel company, so I would have thought they should know what they are talking about. Any body know what is correct ?

Incidentally, I recommend the Bridgestones given that they are in very good condition with at least half original tread left after 22k. Changing them as they are 11 years old.

Thanks
Ges

 

[Greasytrucker]

I very much doubt 45psi all round is correct if before it was 65psi on the front and 55psi on the rear, it’s nothing to do with steel or alloy wheels. The fact that you’ve changed from 15” to 16” will most probably alter the pressures required but not normally vastly

 

[Greasytrucker]

Motorhome-Van tyre pressures | FIAT Ducato

Starting to get confused about 'recommended' tyre pressures for my van Last week had new tyres fitted to my motorhome. Now I have always run the old Michelin tyres at 55PSI front, and 66PSI rear. Even tyre wear, reasonable (for weight) handling, and did not get too hot on long motorway drives...

www.fiatforum.com

See if that helps at all

 

[RS3100]

45 psi sounds much too low, but the larger tyres will probably be able to run at a lower pressure than the 15 inch tyres for the same given loading.

You don't say what tyre sizes you have fitted, but as an example the Bridgestone 215/70 R15 OEM tyres on my van as supplied by Fiat had very little spare capacity on their load rating vs the maximum authorised rear axle weight (2030kgs vs 2000kgs) and required inflating to 65 psi with 2000kg load on the rear axle.

I changed to 16 inch wheels and 215/75 R16 tyres, and they can run at 58 psi for the same axle load of 2000 kg according to Continental Tyres tyre specification manual. Obviously similar applies to the front tyres as well, and the ride is now much more compliant.

The speedometer is now pretty much 100% accurate, whereas it over-read by around 5% on the original wheels and tyres.

 

[The Panda Nut]

I very much doubt 45psi all round is correct if before it was 65psi on the front and 55psi on the rear, it’s nothing to do with steel or alloy wheels. The fact that you’ve changed from 15” to 16” will most probably alter the pressures required but not normally vastly

I agree Ive never heard even a hint of this ever.

 

[Anthony489]

Hi

I cannot think of a single logical reason why alloy wheels would need different pressures to steel. The change in tyre might have a slight influence, but 45 PSI sounds rather low.

The biggest factor in setting correct tyre pressure is the load (weight) on the tyre relative to its ratings, to avoid an excessive build up of heat or excessive flexing.

The tyre manufacturers should be in the best position to offer sensible advice, as long as you can tell them the loading and the maximum speed you drive at. The exception in the past was Michelin, who seemed to want to play safe and unhelpfully advised some very high pressures. All very well, but the folks at Michelin head office weren't the ones crashing over UK potholes !

For the record, I run Michelin tyres on 15 inch rims at 60 PSI all round. The motorhome is about 3300 kg total and fairly evenly distributed between front and rear.

 

[Gessie]

Hi

I cannot think of a single logical reason why alloy wheels would need different pressures to steel. The change in tyre might have a slight influence, but 45 PSI sounds rather low.

The biggest factor in setting correct tyre pressure is the load (weight) on the tyre relative to its ratings, to avoid an excessive build up of heat or excessive flexing.

The tyre manufacturers should be in the best position to offer sensible advice, as long as you can tell them the loading and the maximum speed you drive at. The exception in the past was Michelin, who seemed to want to play safe and unhelpfully advised some very high pressures. All very well, but the folks at Michelin head office weren't the ones crashing over UK potholes !

For the record, I run Michelin tyres on 15 inch rims at 60 PSI all round. The motorhome is about 3300 kg total and fairly evenly distributed between front and rear.

Thanks for the advice. I am getting the Van weighed later, and will check the actual axle weights and limits. Since the 15" steel wheels and 225/70/15s were on it from new I never considered having to recalculate pressures when changing to alloys and 16"s. If I am still puzzled after checking the weights I'll come back here.

 

[rayc]

If you have alloy wheels from new fitted with 2225/70 R16 CP tyres then the Fiat tyre pressure plate will show pressures exactly the same as they were for the 15" steel wheels

 

[SBQ]

Fiat Ducato 2013 year, MultiJet 130 campervan (NOT the Maxi van chassis). For those in this camp, the PDS stud pattern on these vans are different to the factory Maxi Ducato vans that are already on 16" wheels.

Long ago when Fiat came out with alloy wheels with the smaller PDS stud pattern for our vans, I ordered them right away and put them in storage. At around 56,000 miles I changed the original Bridgestone tires. I can think of a time where I was able to own a vehicle, and completely use it for over 10 years whole and whole, without getting a tire puncture. All I did was rotate them but with my previous garage mechanic, I was impressed on how long they lasted and a lot of that was due to luck. So when it came to replacing the wheels, I brought out the alloys which were in storage for I think at least 7 years.

I did the changed to 16" alloys last year and wow it was a massive difference in ride! The original Bridgestones Duravis were 215/70/R15 with a load rating of 109/107S The new tires I went with Michellin Agelis3 215/75/R16C with a much higher load rating of 113/111T

In answering the question on tire pressure. I would say look to the load rating of the tire as an indication at what tire pressure you should be at. I can't see going to 45 psi would have any benefit than a softer more smooth ride, at the expense of lower fuel economy and possibly more tire wear.

 

[Gessie]

Fiat Ducato 2013 year, MultiJet 130 campervan (NOT the Maxi van chassis). For those in this camp, the PDS stud pattern on these vans are different to the factory Maxi Ducato vans that are already on 16" wheels.

Long ago when Fiat came out with alloy wheels with the smaller PDS stud pattern for our vans, I ordered them right away and put them in storage. At around 56,000 miles I changed the original Bridgestone tires. I can think of a time where I was able to own a vehicle, and completely use it for over 10 years whole and whole, without getting a tire puncture. All I did was rotate them but with my previous garage mechanic, I was impressed on how long they lasted and a lot of that was due to luck. So when it came to replacing the wheels, I brought out the alloys which were in storage for I think at least 7 years.

I did the changed to 16" alloys last year and wow it was a massive difference in ride! The original Bridgestones Duravis were 215/70/R15 with a load rating of 109/107S The new tires I went with Michellin Agelis3 215/75/R16C with a much higher load rating of 113/111T

In answering the question on tire pressure. I would say look to the load rating of the tire as an indication at what tire pressure you should be at. I can't see going to 45 psi would have any benefit than a softer more smooth ride, at the expense of lower fuel economy and possibly more tire wear.

Ok Thanks for the information.

 

[Gessie]

I had my Camper weighed , was 2.94 tonne. Not able to weigh the axles. The plate says 3300 kg 5800 kg 1750 kg 1900 kg. I imagine the latter 2 are the axles. With my Bike and some other stuff I guess I will be adding another 75kg when travelling . Does that sound OK weight wise on the new alloy wheels and 225/65 16" tyres ? Thanks.