Tyre Pressures

by streetglider Tue Feb 16, 2021 8:50 am

Firstly a salute to all those involved in this continuing rage against the TPMS on some vans.

Now a thought about insurance so let me give you two scenarios :-

1. I inflate my tyres to the pressure indicated by the vehicle manufacturer (some 40% above the tyre manufacturer's recommendation). I'm involved in an accident (perhaps in rain/ice). The police discover my tyres over inflated.

2. I inflate my tyres to the pressure indicated by the tyre manufacturer (some 30% below the vehicle manufacturer's recommendation). Same accident, same discovery by the police though this time the tyres are under inflated.

Could the police prosecute me for wrongly inflated tyres and charge me with driving a dangerous vehicle ? Could they in turn advise my insurance company and could they (with a reputation of wriggling out of claims) dismiss any claim I may have.
Perhaps I'm being a bit paranoid but I've just read 'Honest John's' column in the Daily Telegraph where he stated 'never over inflate your tyres'.

Just one more thought - what happens with the hundreds (if not thousands) of Peugeot commercial vehicles in this country which have a similar TPMS and whose axle weights vary considerably throughout the day.

Don

by BobK Tue Feb 16, 2021 9:08 am

With the greatest of respect, Don, I think your last sentence in the second last paragraph sums it up hugegrins

by marconi Tue Feb 16, 2021 11:08 am

streetglider wrote:Firstly a salute to all those involved in this continuing rage against the TPMS on some vans.

Now a thought about insurance so let me give you two scenarios :-

1. I inflate my tyres to the pressure indicated by the vehicle manufacturer (some 40% above the tyre manufacturer's recommendation). I'm involved in an accident (perhaps in rain/ice). The police discover my tyres over inflated.

2. I inflate my tyres to the pressure indicated by the tyre manufacturer (some 30% below the vehicle manufacturer's recommendation). Same accident, same discovery by the police though this time the tyres are under inflated.

Could the police prosecute me for wrongly inflated tyres and charge me with driving a dangerous vehicle ? Could they in turn advise my insurance company and could they (with a reputation of wriggling out of claims) dismiss any claim I may have.
Perhaps I'm being a bit paranoid but I've just read 'Honest John's' column in the Daily Telegraph where he stated 'never over inflate your tyres'.

Just one more thought - what happens with the hundreds (if not thousands) of Peugeot commercial vehicles in this country which have a similar TPMS and whose axle weights vary considerably throughout the day.

Don

Justified paranoia I think.

When you do get the TPMS adjusted tell your Insurer why and give them documentation of the Tyre Manufacturers correct pressures / advice, they will be happy with the change, keep documented evidence of the correct pressures and the Insurers acceptance in the van.

TPMS is an Option from Peugeot for Passenger vehicles, it not a requirement for Goods vehicles.

by Roopert Tue Feb 16, 2021 11:47 am

I understand that the situation with Peugeot is frustrating but, in reality, neither situation is likely to result in any action at all from the police. They would want to take action in instances where 1) the driver was doing something deliberately stupid or 2) where the driver was being negligent (e.g. simply not checking whether the pressures were too low or too high).

In this situation, you could easily show that you were taking professional and (supposedly) competent advice on the subject, so it seems extremely unlikely that the police would prosecute.

by Caraman Tue Feb 16, 2021 8:11 pm

streetglider wrote:
Just one more thought - what happens with the hundreds (if not thousands) of Peugeot commercial vehicles in this country which have a similar TPMS and whose axle weights vary considerably throughout the day.

Don

My understanding is as follows:

It is not practical for the driver of a commercial vehicle to continually alter their tyre pressures to reflect their varying load throughout the day. So only one pressure is used for the maximum load, it being less dangerous for a tyre to be over-inflated for its load than under-inflated. The same principle applies to motorhomes which unlike commercial vans have a permanently heavy load.

Boxers and Ducatos registered as commercial vehicles do not have to have TPMSs and therefore are rarely fitted to them. The same applies if they are converted into motorhomes that are registered as commercial vehicles e.g. Auto-Trails. So the TPMS problem is largely confined to motorhomes registered as passenger vehicles like Auto-Sleepers.

Commercial Boxers/Ducato vans will also have standard C tyres, as motorhomes used to have, rather than specialist CP tyres that are now supplied with vehicles destined to be motorhomes. For a 215/70 R15 tyre the plated front pressure is 4.3 bar (C) or 5.0 bar (CP) and the rear 4.5 bar (C) or 5.5 bar (CP). These pressures are for when the axles are at their MTPLM of 1850 kg front and 2000 kg rear plus a bit extra to account for uneven loading across the axle and some overloading. Using ETRTO/Continental figures, the plated front pressure for the C tyre is for an axle mass that is 7.5% higher than the MTPLM. The plated rear pressures for both the C and CP tyre are for an axle mass that is 3% higher. It would probably be higher than this if 4.5 bar and 5.5 bar were not the maximum permitted pressures for the C and CP tyre. The problem is largely confined to the the plated front CP tyre pressure of 5.0 bar which using ETRTO/Continental figures is for an axle mass that is 15.9% higher which is higher than the tyre's maximum permitted load of 1030 kg. If it was only 7.5% higher as for the front C tyre, the plated front CP tyre pressure would be about 4.5 bar. It is not known why the plated CP tyre pressure is 0.5 bar higher than this. It may be because motorhomes have a greater reputation for being overloaded than commercial vehicles but this is pure speculation.

The TPMS problem combined with the high plated front CP pressure is more acute for coachbuilt motorhomes than PVCs. This is because the weight distribution between the axles on a fully loaded PVC is relatively even if not front heavy. This means that when fully loaded the front axle mass can be close to its MTPLM of 1850 kg. The same does not apply to most Auto-Sleepers coachbuilts which when fully loaded tend to be front light and rear heavy. Their front axle mass cannot exceed 1500 kg without the rear axle MTPLM of 2000 kg being exceeded and in some cases their fully loaded front axle mass is well below 1500 kg. For example, my fully loaded Nuevo EK has a front axle mass of only 1375 kg. Tyresafe recommend that the pressure set for motorhomes should be for an axle mass that is 10% higher. If I follow this recommendation my front tyre pressures should be no higher than about 3.2 bar. If I ignore the 10% recommendation they should be 3.0 bar. Before I had my TPMS adjusted, I couldn't get my front pressures below 4.3 bar without the TPMS triggering.

In summary, the problem is not for the 1000s of Peugeot commercial vehicles but it is for the 1000s of Peugeot & Fiat coachbuilt motorhomes registered as passenger vehicles which, unlike Bailey motorhomes, have not had their front TPMS adjusted as part of their conversion.

by Cymro Tue Feb 16, 2021 8:15 pm

A masterly exposition, Caraman. Thank you.

Cymro

by streetglider Wed Feb 17, 2021 4:51 pm

Thank you Caraman, logically, clearly and thoroughly explained.

Don

by Paulmold Thu Feb 18, 2021 8:21 pm

Just read this on another forum...

"If you come across a Peugeot dealer who doesn't know how to configure the TPMS using their own Diagbox kit (to be fair it is quite well hidden) then you could always give them a lesson - but negotiate a discount first!

Select vehicle type then:
'Repair > Test by ECU > Under-inflation detection > Repair > Spare part > Reading of the reference pressure of the tyres'
and 'Setting of the reference pressure of the tyres'.

"

by Caraman Thu Feb 18, 2021 9:05 pm

That could be useful. The dealer who did mine couldn't explain the difference between the 'reference pressure' and the 'reference pressure high speed'. The factory setting was the plated pressure and the same for both. Nor could they tell me the pressure the TPMS would actually trigger. My rear pressures are still set to the plated 5.5 bar but I know I can run them at 5.0 bar without triggering and possibly lower still but I don't need to go that low.

by Kdc Thu Feb 18, 2021 9:58 pm

That .5bar difference between plated and your dropped pressure fits with my experience......my plate state 62R and I run 55 and have had no issues. Hope I hav’nt spoken too soon,

by marconi Tue Feb 23, 2021 11:00 am

Have Bailey only recently started doing the job properly and having the TPMS adjusted correctly on their Peugeot chassis. If so what made them do it I wonder, or is it a myth.

I remember Steve (he doesn't often pop up on here), saying that the same TPMS problem is a big concern to Bailey owners.

I have confirmed this, just a few brief clips of recent comments.

Anyone managed to adjust their tyre pressures successfully, i.e. without having a constant warning light on in the instrument panel

many people frustrated by the tpms system and their inability to adjust the on board system themselves

Remember tyre pressure is governed by a combo of axle weight and tyre load rating. It's not something that you can just make up.

set the fronts at 60psi and rear at 70psi, travelled 200 miles with the pressure warning light on all the way

Ride is much improved with slightly lower pressures

Sounds just like this Forum to me.

I get the impression that it is a British Converters penny pinching thing, with just same devil may care attitude to safety.

by Caraman Tue Feb 23, 2021 11:13 am

I have seen it with my own eyes that Bailey re-plate their tyre pressures. This is what they told me in Sep last year:

Due to extensive testing, and with the assistance of both the tyre manufacturers and the change of weights and work carried out with Peugeot, the tyre pressures have been recalculated to reflect the changes from a standard Boxer van to our motorhome. When the vehicle has its Peugeot PDI they adjust the TPMS system to reflect the amended pressures. At the beginning of each new motorhome range the tyre pressures become part of the overall VWTA ( vehicle whole type approval ) sign off by the independent testing house.

I hope this helps explain our change of tyre pressures.

by marconi Tue Feb 23, 2021 1:35 pm

Caraman wrote:I have seen it with my own eyes that Bailey re-plate their tyre pressures. This is what they told me in Sep last year:

Due to extensive testing, and with the assistance of both the tyre manufacturers and the change of weights and work carried out with Peugeot, the tyre pressures have been recalculated to reflect the changes from a standard Boxer van to our motorhome. When the vehicle has its Peugeot PDI they adjust the TPMS system to reflect the amended pressures. At the beginning of each new motorhome range the tyre pressures become part of the overall VWTA ( vehicle whole type approval ) sign off by the independent testing house.

I hope this helps explain our change of tyre pressures.

Yes I remember that.

These boys don't quote their year of manufacture or whether they are Alco chassis jobs the only clue is one model number 75-2 sounds like a 2 birth.

They suffer all the same refusals from Peugeot etc. mind you I think Peugeot are right, they have carried out their part properly.

by Caraman Tue Feb 23, 2021 2:36 pm

Bailey's current and archived motorhome handbooks can be seen here:

https://www.baileyofbristol.co.uk/owners-manuals-and-service-handbooks/

As far as I can gather Bailey started building motorhomes in 2011. Prior to this they only made caravans. They seem to have only ever used the Peugeot Boxer but with an AlKo chassis and rear axle. So Peugeot do the stage 1 type approval, AlKo stage 2 and Bailey stage 3. The earliest 2012 handbook shows that Bailey has as part of their stage 3 type approval/conversion changed the stage 1 tyre pressure label. I know from talking to AlKo that they do not change the stage 1 tyre pressure label because the habitation load hasn't been added at that stage. The front CP tyre pressures Bailey has recommended may have changed over the years but they have always been less than Peugeot's stage 1 type approved pressure of 5.0 bar. The 2019 and subsequent handbooks give detailed front tyre pressures for each of their models. I might have missed it but I don't think there is any reference in the handbooks to the TPMS. My understanding is that TPMSs only became mandatory for motorhomes registered as passenger vehicles from 2014/5. I don't know how long Peugeot has been supplying the current TPMS but presumably they have since 2014/5. None of this explains why some Bailey owners apparently had problems with their TPMS setting unless it was just that on some models the stage 3 type approved front tyre pressure, whilst lower than the Peugeot stage 1 pressure, wasn't low enough.

by marconi Tue Feb 23, 2021 3:36 pm

Caraman wrote:Bailey's current and archived motorhome handbooks can be seen here:

https://www.baileyofbristol.co.uk/owners-manuals-and-service-handbooks/

As far as I can gather Bailey started building motorhomes in 2011. Prior to this they only made caravans. They seem to have only ever used the Peugeot Boxer but with an AlKo chassis and rear axle. So Peugeot do the stage 1 type approval, AlKo stage 2 and Bailey stage 3. The earliest 2012 handbook shows that Bailey has as part of their stage 3 type approval/conversion changed the stage 1 tyre pressure label. I know from talking to AlKo that they do not change the stage 1 tyre pressure label because the habitation load hasn't been added at that stage. The front CP tyre pressures Bailey has recommended may have changed over the years but they have always been less than Peugeot's stage 1 type approved pressure of 5.0 bar. The 2019 and subsequent handbooks give detailed front tyre pressures for each of their models. I might have missed it but I don't think there is any reference in the handbooks to the TPMS. My understanding is that TPMSs only became mandatory for motorhomes registered as passenger vehicles from 2014/5. I don't know how long Peugeot has been supplying the current TPMS but presumably they have since 2014/5. None of this explains why some Bailey owners apparently had problems with their TPMS setting unless it was just that on some models the stage 3 type approved front tyre pressure, whilst lower than the Peugeot stage 1 pressure, wasn't low enough.

As I understood it from Steve, the situation with Bailey was the same as we have.

Historically I see people complaining in 2017, 2018 and 2019. With such comments as I clipped above and those below which seem to confirm the same Peugeot base vehicle figures too.

Certainly the examples of dropping front pressure to 60psi (4.13 bar) and getting a trigger of the TPMS fits perfectly with the original front pressure being 72.5 psi (5 bar) Peugeot stage1 pressure and the known trigger margin.

It seems if you complained enough Bailey sent some customers for free adjustment to their pet Peugeot Dealer in Bristol.

"If you search for tpms there is a post that states Robins and Day of Bristol reduced the tpms from 80 to 60 psi"

"Just back from Peugeot in Grantham, they have lowered the values at which the TPMS alarms, so I can run lower pressures if desired. It only took 30 mins, the ride back at 65/60 instead of 80/69 was a revelation"

Looking at the 2018 Bailey Handbook I see the recommended Front tyre pressure is 69 psi this can used as we know without any change to the first stage figure. If the TPMS had been adjusted to suit 69 psi then the trigger pressure would be 54.5 psi not 60 psi.

So it would seem that they did not carry out stage 3 type approvals until 2019, I haven't seen any complaints in 2020. I am still wondering what made them do it, maybe customer complaints.

by Caraman Tue Feb 23, 2021 5:00 pm

Yes - it's not an entirely clear picture. The 2012 handbook clearly shows a Bailey stage 3 type approved tyre pressure label with a front pressure of 55 psi. This is what it states:

Tyre Pressures: Your Bailey motorhome is fitted with Michelin Agilis Camping tyres. These tyres are designed to run at 80 Psi on the rear axle for all all loads when used in a single fitment. The front tyre pressure can be set depending on the maximum in-service vehicle loads. The cold tyre pressures for your vehicle are labelled on the inside of the passenger door frame. The tyres are 215/70 R15 CP 109Q

So from this it appears that Bailey has always carried out stage 3 tyre pressure type approvals. The bit that is not clear is from when did the TPMS arrive and from when was the TPMS adjusted as part of the conversion to match the stage 3 tyre pressure label.

by marconi Tue Feb 23, 2021 5:55 pm

Caraman wrote:Yes - it's not an entirely clear picture. The 2012 handbook clearly shows a Bailey stage 3 type approved tyre pressure label with a front pressure of 55 psi. This is what it states:

Tyre Pressures: Your Bailey motorhome is fitted with Michelin Agilis Camping tyres. These tyres are designed to run at 80 Psi on the rear axle for all all loads when used in a single fitment. The front tyre pressure can be set depending on the maximum in-service vehicle loads. The cold tyre pressures for your vehicle are labelled on the inside of the passenger door frame. The tyres are 215/70 R15 CP 109Q

So from this it appears that Bailey has always carried out stage 3 tyre pressure type approvals. The bit that is not clear is from when did the TPMS arrive and from when was the TPMS adjusted as part of the conversion to match the stage 3 tyre pressure label.

2012 Golly I haven't been back that far.

Now, this shows that Bailey were carrying out stage 3 approvals back in 2012, not "always", there is even a label and a figure of 55 psi Front that proves that year only, so when and why did that figure in later years leap up to 69 psi.

Perhaps we should be looking for the date when EU legislation changed and the Converters found a loop hole to avoid stage 3.

by Caraman Tue Feb 23, 2021 8:38 pm

I have just gone through all the on-line handbooks which was very dull!

The 2012, 2013 & 2014 handbooks showed examples of Bailey's stage 3 tyre pressure label. The 2012 handbook showed a front CP pressure of 55 psi and the 2013 & 2014 handbooks showed 60 psi. The 2017 handbook didn't show a stage 3 tyre pressure label but specified a front CP pressure of 69psi. I was incorrect earlier about the 2019 handbook as it makes no reference to the tyre pressures. The 2020 & current handbooks give a detailed breakdown by model showing a front CP tyre pressure of 50 psi for all models less the 6-berth/seat models which are 55psi.

As I said earlier, the Bailey recommended pressures may have changed but they must be stage 3 type approved pressures as per the labels shown in the 2012, 2013 & 2014 handbooks as in all cases they are less than the 73 psi (5.0 bar) Peugeot stage 1 type approved pressure.

Converters must seek stage 3 type approval if the base vehicle has a stage 2 type approved AlKo chassis and rear axle and stage 2 type approval if the base vehicle still has its stage 1 type approved chassis and rear axle. So the Nuevo and Broadways are subject to A-S stage 2 type approval and the Corinium is subject to A-S stage 3 type approval.

by marconi Tue Feb 23, 2021 10:48 pm

Well done, I found looking at 2 or 3 rather dull, yet oddly interesting seeing real instruction books that actually apply to the model and change every year, Bailey are obviously putting proper professional effort into their product, and have got it right now with the TPMS.

Did the advent of TPMS throw the homologation engineers into confusion, the 69 psi dates tie up with the complaints period. It seems the TPMS wasn't adjusted so the type approval was either not done, or was not done properly, that would be a waste of money and the figures would have to be fiddled.

Now where have we come across a confused homologation engineer making illogical excuses.

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