Roller team 746

[ChrisD]

Hello all

 

I recently collected a brand new roller team 746. We love the camper but the ride seems quite noisy and hard. Not just the usual rattles we get with campers. I have done the obvious and checked tyre pressures but wondered if anyone else has experience with one of these. Its great below 30mph but after that it can be noisy.

 

Thank you for all help

[Keithl]

Chris,

 

To help us help you, what chassis is your Roller Team built on, what size of tyre does it have and finally what pressures are you running at?

 

Keith.

 

Edit to add, and are the tyres C or CP?

[Derek Uzzell]

The 2017 RollerTeam brochure can be found here

 

https://www.rollerteammotorhomes.co.uk/media/downloads/Rollerteam-brochure-2017.pdf

 

and includes a reasonably comprehensive technical specfication for all models including the Auto-Roller 746.

 

The chassis is Fiat’s Ducato X290 ‘light’ camping-car type with a maximum overall weight of 3500kg or 3650kg.

 

The standard wheel-size is 15” diameter, when the tyres wiill be the usual 215/70 R15CP specification. It’s possible that optional 16”-diameter wheels may have been fitted, when the tyres would be 225/75 R16CP spec.

 

The tyres’ manufacturer is probably Continental and the tyres would then be “VancoCamper” pattern. (If Michelin tyres are fitted, they will be ”Agils Camping” pattern and have a similar size/specification to the Continentals.)

 

The recommended inflation-pressures for the tyres (Continental or Michelin) will undoubtedly be 5.0bar (front axle) and 5.5bar (rear axle) for 15”-diameter wheels, or 5.5bar (front and rear axles) for 16”-diameter wheels.

 

Although the 746 is a large motorhome, if the reccommended tyre inflation-pressures are adhered it’s pretty much inevitable that - except when driving on very smooth road surfaces - the ride will be harsh and anything inside the vehicle that can rattle will.

[ChrisD]

Hello Keith and Derek

 

Thank you both for your replies.

 

Derek is absolutely spot on. the tyres are215/70 R15 Michelin "Camping".

They are inflated to 5 and 5.5 bar.

 

I think that answers it perfectly.

 

Thank you again

 

Chris

[Robbo]

Michelin will always recommend 5.5bar (80psi) for their camping tyre on the rear axle whatever the actual load.

 

However, they will give you a realistic pressure for the front axle if you provide them with the axle load in fully loaded touring trim.

 

So, best to load up with all passengers + kit onboard, full fuel, full water and visit a weighbridge.

 

For a 3500Kg chassis I would roughly estimate 4bar front and 5bar rear.

 

But, don't take my word for it - you need to do a bit of legwork first to satisfy yourself before reducing pressures.

 

PS. I guess your permissible axle loads are 1850F and 2000R as shown on the Rollerteam vin plate. Also, the load index of the tyres are at least 109.

 

 

[ChrisD]

Thanks Robbo

 

I went to the Weighbridge this afternoon.

The vehicle was completely empty. No kit or personal effects.

No water or gas.

3/4 Tank of fuel and 4.5m Awning. 2 Slight passengers and myself.

Total weight 3240KG

 

Going to be close to weight so I think the Michelin tyre pressures are here to stay.

 

Thanks for the thought though

[Derek Uzzell]

The reasoning behind Michelin’s stance in advising that a 5.5bar inflation-pressure must be used for their “Agilis Camping” tyres when fitted to a vehicle’s rear wheels was discussed in this 2016 forum thread

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Tyre-Pressures/42612/

 

Matching pressures for 215/70 R15CP tyres to an Auto-Roller 746’s 1850kg (front axle) and 2000kg (rear axle) maximum axle-loadings would result in 4.1bar (front axle) and 5.5bar (rear axle).

 

I’m pretty confident that the 1850kg front-axle maximum would not be exceeded for a normally-loaded current-model 746, so Chris should safely be able to reduce his motorhome’s front-tyre pressure from 5.0bar to 4.1bar as an experiment. This would soften the ride at the front, but I’m doubtful it would make a significant difference to the present noisiness which is much more likely to result from the 5.5bar rear-tyre pressure.

 

Michelin’s policy is not to advise alternative rear-tyre pressures for “Agilis Camping”, meaning that, even if Chris established that its (fully loaded) rear-axle figure was well below the 2000kg maximum, he still would not be able to get ‘official’ advice from Michelin regarding reducing the current 5.5bar pressure.

 

It’s straightforward to match inflation-pressure to rear-axle loading for Continental’s “VancoCamper’ tyres (the necessary data are on-line) and those values should apply equally well to “Agilis Camper”. What you won’t get is ‘approval’ from Michelin to diverge from the 5.5bar figure, nor to transpose Continental’s data to Michelin tyres.

 

As Robbo has said, if adjusting tyre-pressure to axle-loading is being considered, it will first be necessary to weigh a motorhome in the state that it will normally be operated. (For me that would mean a full fuel tank, full fresh-water tank, full gas bottles, driver/passengers and all the ‘clobber’ (tools, clothes, books, bedding, chairs, etc.) that gets carted around.) Once real-world axle-loadings have been established, it should become apparent whether reducing the specified tyre-pressures is a realistic option.

 

The RollerTeam brochure defines how the quoted weight data are arrived at and I note the statement "Electronic weighing of 100% of the vehicles prior to their delivery and written certification of the weight to the final customer.”

 

It may well be the case that a high rear-tyre pressure will be necessary for a ‘fully loaded’ Auto-Roller 746, but it’s also possible that when the rear-axle gets more weight placed on it the ride will become more subdued.

[Keithl]

Chris,

 

Going on your weights I still think it would be worth contacting Michelin to check on what pressures they recommend for your axle loads.

 

If you look at the generic tyre pressure versus load tables for CP tyres on the last page of the Tyre Safe website, http://www.tyresafe.org/wp-content/uploads/2015/12/motorhome-leaflet.pdf for a 215/70 R 15 CP tyre the maximum recommended axle load is quoted as 2,070 kg at 4.16 bar (60 psi). This load should be well in excess of your max axle load so in theory you should be running your tyres at below 4.16 bar.

There is also a note that states "For inflation pressures relating to lower loads, contact the tyre manufacturer."

 

My opinion but I think your are running your tyres well above the optimum pressure for comfort.

 

Keith.

 

Edit: Crossed posts with Derek.

[ChrisD]

That is very helpful.

 

I need to load and again weigh the camper to determine axle loads.

 

I was trying to avoid doing this as the camper has to be returned to the dealer a week tomorrow a round trip of 200 miles. Empty would be preferable. So on return I will load and weigh.

 

It will be interesting to see if loading the rear axle improves the ride, I had assumed the weight of the build would have done this.

 

So grateful for your informed input.

Regards Chris

 

 

[ChrisD]

Derek

 

As you said Michelin would not approve deviation from their recommended tyre pressures.

Could this be as issue in the event of an accident that the tyre pressures did not match those on the label inside the passenger door?.

 

I'm reasonably confident on the attitude the police would take.

[ChrisD]

Keith

 

I agree and when I have weighed the camper I will contact the manufacturer to see what variation of pressures can be acceptable and to what form of written confirmation can be provided as per the contents of my post to Derek above.

 

I marconsider changing to Vanco although at this stage that would be an extreme measure.

 

Thanks again

Chris

[Derek Uzzell]

The TyreSafe leadflet Keith mentioned above is out-of-date and (where CP-marked tyrers are concerned) inaccurate.

 

The leaflet suggests that - for ‘single-wheel’ axles (ie. an axle with a single wheel at each end) - there are two sets of inflation-pressures, with a special set of pressures applying only to DRIVEN single-wheel rear axles. There was some confusion about this when the “CP” marking was initially introduced some years ago, but the true situation is that, although Continental (and presumably Michelin) indeed has two sets of pressures for CP-marked tyres fitted to single-wheel axles (one for front axles and a 2nd for rear axles) the latter set of pressures applies irrespective of whether the rear axle is ‘driven’ (eg. on Keith’s Mercedes) or ‘’dead’ as on all front-wheel-drive motorhomes.

 

The ETRTO’s late-2014 advice reads as follows

 

“The LI designation of CP-type tyres carries a single “load index” indicating their normal use in single fitment. In this case only, tyres on the rear axle have to be inflated to 550 kPa (5.5 bar), (to compensate for severe conditions of unequal load distribution, but with no further concession to increase the maximum load capacity)...”

 

There is nothing to suggest that this advice applies only to driven rear axles.

 

A 215/70 R15C “Agilis Camping” or “VancoCamper” tyre has a load-index of 109 that indicates that the tyre has been designed (and tested) to carry a maximum load of 1030kg, translating to 2060kg maximum axle-loading for a single-wheel axle.

 

Continental’s 2016/2017 relevant Technical Databook can be found here

 

http://tinyurl.com/mbdmw74

 

and data relating to the 215/70 R15CP VancoCamper tyre are on Pages 78 and 79.

 

There is a pressure-to-axle-load set of values that relate to “FA S” (Front Axle Single-wheel) and range from 3.0bar for an axle-load of 1425kg to 4.75bar for an axle-load of 2060kg.

 

A second set of pressure-to-axle-load values relates to “RA S” (Rear Axle Single-wheel) and those values range from 3.0bar for an axle-load of 1270kg to 5.5bar for an axle-load of 2060kg.

 

The Continental data for their 215/70 R15CP tyre equate near-as-dammit to the data for the same size/type tyre in the TyreSafe leaflet, which just indicates that all 215/70 R15CP tyres (Continental or Michelin) will have a similar technical pressure-to-load specification. I’ve no idea how a motorhome buyer is expected to react to the Tyre Safe leaflet’s statement

 

"Note: Figures in bold black are recommended maximum loads. Figures in bold red are absolute maximum loads.”

 

Regarding the potential impact of choosing to use tyre-pressures that differ significantly from those ‘labelled’ on the motorhome or advised in the vehicle’s handbook, I believe I addressed this in my final posting here:

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Tyre-Pressures/42612/

 

At this point (if there’s concern about ‘legality’) the sensible thing to do would be to stick to the advised 5.0bar/5.5bar pressures until the 746’s fully-loaded axle-loadings can be established. Once those figures are known it should become apparent whether safely reducing the 5.0/5.5 pressures will be a realistic option.

 

An Auto-Roller 746 is a large overcab design with 5 designated travel seats and 6 berths. It is 7.35m long and 3.2m high, with a basic Mass in Running Order of 3075kg (including allowances for a 75kg driver, full fuel-tank, one 13kg gas-cylinder and 20 litres of water). The 215/70 15” tyre-size is hardly generous for this size/design of motorhome and, frankly, it would be very optimistic to anticipate being able to safely use tyre pressures (on the rear axle at least) that were significantly lower than those advised by the manufacturer.

[ChrisD]

Thank you Derek and as always informative, concise and very helpful.

 

I read your previous post and the last sentence said it all!

 

Chris