TPMS and the spare wheel

[Steve928]

My van was supplied with TPMS sensors in its 4 road wheels but not in the spare wheel. I'd always assumed that this was a cost-cutting measure, but apparently not.

Having ended-up with a spare TPMS sensors I thought it would be good to fit one to the spare wheel so it could be used, in the event of needing or wanting to use the spare, without triggering a TPMS error.

 

Peugeot have confirmed though that the presence of a 5th. TPMS-equipped wheel will trigger the TPMS warning light. You can physically fit the sensor but it must be de-programmed and if you then mount the wheel it must be re-programmed and the wheel it has replaced must be de-programmed..

 

Far from ideal in my opinion but that's the way it is. Just for information.

[Brian Kirby]

As the target pressures are pre-set, and have caused some annoyance for those who prefer to run at lower than the pre-set pressures, is the option do de/re program the sensor open to anyone to do, or does it have to go to a dealer to be done?

 

Just wondering if de-programming the lot (and relying on a pressure gauge - as those of us still in the stone age do :-)) might offer a work-around for those affected?

[Steve928]

I believe that any tyre depot with the relevant Schrader equipment can activate or de-activate wheel sensors but that you need to visit your dealer to have the alarm thresholds re-programmed in the Body Systems Interface.

 

Just de-activating the wheel sensors would be functionally equivalent to running without wheel sensors, I would have thought, and that will leave the TPMS warning light on.

[Derek Uzzell]

The TPMS system fitted to Boxer/Ducato/Relay vehicles was discussed in some depth here

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/X290-tyre-pressure-reset-/40276/#M498561

 

It would appear from this Fiat 500-related link

 

http://www.fiatia.com/fman-320.html

 

that, when a full-size spare wheel is provided as original equipment on a Boxer, it is being treated by Peugeot (and presumably by Fiat with Ducato) as if it were a ’skinny’ emergency-only spare wheel.

 

In the latter case no TPMS sensor is fitted to the spare wheel and it is anticipated that, after the problem that caused the emergency-only spare wheel to be mounted has been addressed, the emergency-only spare wheel will be dismounted and a full-size wheel with a TPMS sensor will be mounted in its place.

 

The TPMS section of the Fiat Owner Handbook for my 2015 Ducato (that does not have the TPMS option) advises that “the space-saver wheel is not equipped with the tyre pressure control sensor”, but Ducatos do not have that type of wheel and no mention of full-size spare wheels is made.

[Rayjsj]

All sounds very complex for what is after all a normal driver service requirement , check tyre pressures and adjust to prevelent conditions, ie. In deep snow or mud, lower pressure until sufficient grip is restored. Bet the ECU doesnt know that one ! One particular accessory i will not be fitting, or if its fitted already, one i will be disabling, especially if i have no control over ideal tyre pressures for relevent conditions. An unecessary extra thing to be added to the bill ! Perfect for HGVs but on cars and light commercials, not required.

[Derek Uzzell]

Ray

 

Historic motoring ploys - like putting a vehicle into gear and using its starting-handle to ‘wind’ it out of deep sand - can become obsolete as the standard specification of vehicles alters.

 

Nowadays a vehicle manufactuer will expect a driver to periodically check tyre pressures and will very likely mention this in the vehicle owner’s handbook. If the driver fails to do this and the pressures fall significantly (or a tyre loses pressure unusually) the TPMS will provide a warning.

 

With cars different tyre pressures are often specified for a particular tyre size, with an increase in the ‘base pressure’ being advised to meet an increase in the load the car is carrying. (The base pressures for my Skoda car’s tyres relate to two people being on board and - if four people and all their luggage are to be carried - the front tyes should be inflated slightly higher and the rear tyres much higher.) As the advise relates to increasing pressure, not lowering them, a pressure-sensitive TPMS system should have no problem with that approach. But multiple tyre pressures are not advised by manufacturers of light commercial vehicles - there’s just one recommended tyre pressure per axle, commonly based on the axle’s maximum authorised loading.

 

There has never been a “normal driver service requirement” to optimise road-vehicle tyre pressures to better cope with prevalent weather/road-surface conditions. And the vehicle manufacturer will certainly never advise an owner of a common-or-garden road-vehicle to lower tyre pressures to aid grip in deep snow or mud (which will be ineffective anyway unless the tyre is pretty much ‘flat’.) And, if you attempted the ‘flat tyre’ trick with a motorhome, it would be educational (and probably entertaining) to see you try to raise the pressures in the driven-wheel tyres from, say, 10psi to 60psi.

 

Like it or not TPMS will be become unavoidable on new motorhomes and, although it should be practicable to alter TPMS pressure-sensors to meet a vehicle owner’s requirements, it’s to be expected that this facility will not be ‘owner controlled’. (And I’d say nor should it be.) I don’t think you would be able to legally disable a TPMS system, and I’m doubtful that you could do it technically.

 

So if you ever change your 2014 motorhome for one that has TPMS I believe you’ll need to grit your teeth and tolerate how the system operates and live with whatever driver interaction the system allows.

[Rayjsj]

The recommended tyre pressures on my present van are 4.75 bar, and this is what they were set to when we picked it up.

The ride was horrendous, so much so that we thought we had faulty suspension, so we went back to the dealer. No, he said its meant to be like that !!! And 4.75 bar is the STIPULATION from Fiat. I am seriously considering getting progressive load assistor springs (MAD) or even Air assistance , similar to what Autosleeper fit as standard. To try and smooth the ride down a bit.

Until then i have been experimenting with lower tyre pressures, i find Bar too large a graduation and have reverted to lbs per square inch. At the moment i am running on 68 psi (cold) which gives a better ride, and good mpg, And does not run too hot.

Always quoting max load pressures does not make for a comfortable journey. Having that backed up by failng the MOT, AND having an adjustment taken out of my hands, to me, is not acceptable.i will stick with my 2014 vehicle thanks.

And as the op says, no provision for fitting a full sized spare wheel......words fail me.

[Derek Uzzell]

The only mention I can find of a 4.75bar tyre-inflation recommendation in a Fiat Ducato Owner Handbook appropriate to a 2014 model (X250 or X290 version) is when a Ducato has 225/70 R15C tyres and these are "Winter tyres M+S class C on Camping vehicle”. The advised pressures are then 4.3bar (front tyres) and 4.75bar (rear tyres).

 

I don’t know how to interpret your statement

 

"Until then i have been experimenting with lower tyre pressures, i find Bar too large a graduation and have reverted to lbs per square inch. At the moment i am running on 68 psi (cold) which gives a better ride, and good mpg, And does not run too hot.”

 

4.75bar is (roughly) 68.9psi, so I suspect you are experimenting with pressures well below 68psi. Certainly, to produce a noticeable ’softening’ of the ride, I’d anticipate that it would be necessary to reduce the 4.75bar rear-tyre pressure down to at least 4.0bar (58psi).

 

It’s unrealistic to expect a vehicle manufacturer who is legally compelled to fit a safety-related system like TPMS to include within that system a facility for the vehicle’s owner to make massive alterations at will to the system’s original pressure settings. It is apparently practicable to have a Boxer’s/Ducato’s TPMS reprogrammed to deal with owner-chosen (or motorhome converter chosen) lower tyre pressures, so the tyre pressures are not set in stone.

[bigparkie]

On the ford the user can reset the system after adjusting pressures to his/her desire it then checks for deflation which could occur 10 minutes after checking.to my mind this is a very useful system.

Richard

[Steve928]

My mother reset a TPMS alarm and continued driving her Mini Cooper S for 6 months with no air in one tyre. None at all, 0psi. She had no idea that she had Runflat tyres and presumed that were it a genuine puncture the tyre would look flat.

[Derek Uzzell]

As the Ducato TPMS system seems (based on the Owner Handbook) to cover just 4 wheels fitted with pressure-sensors, it might be worth knowing what happens when a Ducato motorhome with a 6-wheel tandem-axle Al-Ko chassis has to legally have TPMS. Do just 2 of the 4 rear wheels have TPMS sensors, or what?

[goldi]

Afternoon folks,

 

I,m glad my van does not have this gadget. Mrs goldi,s car has got it and when the light came on I put some more air in the tyres, not that much was needed anyway to the required pressure and it still did not go out so off it went back to the dealer to get sorted. What a palaver.

 

 

 

norm

[Derek Uzzell]

And resetting the TPMS system on the latest Ford Transit may not be as straightforward as the Owner’s Manual seems to suggest

 

https://www.google.co.uk/?gws_rd=ssl#q=ford+transit+tpms

 

No TPMS using pressure-sensors is going to allow the vehicle-user complete freedom to alter the tyre pressures recommended by the vehicle’s manufacturer.

 

It should be obvious that if (say) 80psi is recommended by Fiat for a Ducato-based motorhome’s rear tyres and the motorhome owner decides to run those tyres at 50psi to obtain a softer ride, if TPMS is fitted to the motorhome the system is most unlikely to tolerate a 30psi reduction and not issue a warning. There’s bound to be a bit of ’slack’ in a pressure-sensitive TPMS to cope with tyre-pressure drop caused by changes in the weather, but it’s not likely to be as much as motorcaravanners appear to want.

[malc d]

goldi - 2016-08-15 1:59 PM

 

Afternoon folks,

 

I,m glad my van does not have this gadget.

 

What a palaver.

 

 

 

norm

 

 

 

 

Same here !

 

 

;-)

[Rayjsj]

bigparkie - 2016-08-15 9:15 AM

 

On the ford the user can reset the system after adjusting pressures to his/her desire it then checks for deflation which could occur 10 minutes after checking.to my mind this is a very useful system.

Richard

 

This system sounds good, does what it should without Big Brother interfereance. Like it.

 

[Derek Uzzell]

Rayjsj - 2016-08-15 6:59 PM

 

bigparkie - 2016-08-15 9:15 AM

 

On the ford the user can reset the system after adjusting pressures to his/her desire it then checks for deflation which could occur 10 minutes after checking.to my mind this is a very useful system.

Richard

 

This system sounds good, does what it should without Big Brother interfereance. Like it.

 

Richard has not provided the year of manufacturer of his Ford Transit-based Chausson, but let’s assume it is 2015.

 

The Owner’s Manual appropriate for a 2015 Transit can be viewed here

 

http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/ENUSA_CG3612_Transit_og_201412.pdf

 

and there’s a “Wheels and Tires” section (Pages 181 to 202) that covers the TPMS, tyre specifications/pressures, etc.)

 

The TPMS advice begins

 

"You must check the tire pressures (including the spare tire where applicable) every two weeks when the tires are cold.

 

You must inflate the tires to the correct pressure.

 

See Wheels and Tires (page 181). The tire pressures are also on the tire inflation pressure label (located on the edge of driver door or the B-Pillar).

 

As a driver assistance feature, your vehicle has a tire pressure monitoring system. A warning lamp will illuminate when one or more of the tires are significantly under-inflated. If the low tire pressure warning lamp illuminates, you should stop your vehicle as soon as it is safe to do so, check the tires and inflate them to the correct pressure.

 

Driving on under-inflated tires can:

• Cause them to overheat.

• Lead to tire failure.

• Reduce fuel efficiency.

• Reduce tire life.

• Affect vehicle handling or stopping ability.

 

The system is not a substitute for correct tire maintenance.

 

You must maintain the correct tire pressures, even if low tire pressure has not illuminated the warning lamp.

 

The tire pressure monitoring system has a system malfunction indicator to warn you when the system is not operating correctly. The malfunction indicator and low tire pressure warning lamp have a combined function. When the system detects amalfunction, the warning lamp will flash for approximately one minute and then remain illuminated. This sequence will occur every time you switch the ignition on while the malfunction remains. The system has detected a fault that requires service.

 

When the malfunction indicator is illuminated, the system may not be able to detect or signal low tire pressures. A malfunction may occur for a variety of reasons, including the installation of a replacement tire or wheel that prevents the system from functioning correctly. Always check the tire pressure monitoring system malfunction warning after replacing one or more tires or wheels on your vehicle. Make sure the replacement tires or wheels allow the system to continue to function correctly. See When the Temporary Spare Tire is Installed in this section.”

 

The Manual goes on to say

 

"Understanding the Tire Pressure Monitoring System

 

The system measures the pressure in the four road tires and sends the tire pressure readings to your vehicle.

 

The system detects this lower pressure as being significantly below the correct inflation pressure and the warning lamp illuminates. You must inflate the tires to the correct pressure.”

 

There is guidance in the Transit Manual on how to reset the TPMS and why this may be necessary, but there is nothing in the Manual to suggest that “...the user can reset the system after adjusting pressures to his/her desire...”. The emphasis throughout the Wheels and Tires section is always that the tyres should be inflated to the CORRECT pressure (ie. the pressure shown in the Manual and on the vehicle’s data-plate) and that the TPMS will warn if the CORRECT pressure has fallen significantly.

 

The Transit Manual does not exactly define how “significantly” the correct tyre pressure has to reduce before the TPMS warns of a potential problem, but the “How Temperature Affects the Tire Pressures” paragraph suggests that the tolerated reduction may be quite small.

 

I’m guessing that the Ford recommended inflation pressures (ie. the ‘correct’ pressures) for Richard’s Chausson’s 235/65 R16C tyres are 51psi/3.5bar (front) and 65ps/4.5bar (rear). If Richard is correct that “...the user can reset the system after adjusting pressures to his/her desire...” it should be a simple experiment to first ensure that his Chausson’s tyres are inflated to the ‘correct’ pressures, then reduce one of tyre’s pressure in progressive steps (resettingthe system after each step) and check how the TPMS reacts.

 

If the Transit TPMS accepts total user-control, reducing the ‘correct’ pressure and resetting the TPMS should mean that the user can indeed adjust pressures “...to his/her desire...” and the TPMS will still provide a warning of further pressure reductions beyond what the user has chosen.

 

Much more likely, though, is that a user only has the capability to reduce the ‘correct’ pressures within a relatively restricted preset pressure-range and - once the lower threshold of that range is reached - resetting the TPMS will not stop the system from warning that there is a potential under-inflation problem.

 

Wikipedia has a fair-sized entry on TPMS

 

https://en.wikipedia.org/wiki/Tire-pressure_monitoring_system

 

but - for motorhome owners who feel an overpowering urge to manipulate tyre pressures as if they were driving a F1 racing car - the relevant issue (IMHO) is how much a TPMS interferes with that practice.

 

If a TPMS were to prevent a motorhome being driven should tyre ‘under inflation’ be detected, motorhome owners would have real cause for complaint. If a TPMS produced an irritating loud audible warning should tyre ‘under-inflation’ be detected, and that noise was continuous and impossible to override, there would be good reason to moan.

 

But all the Fiat Ducato/Peugeot Boxer TPMS does (and presumably all the Transit TPMS does) according to the Owner Handbook is to illuminate a symbol on the instrument-cluster display to warn of under-inflation.

 

If an owner of a Ducato/Boxer has deliberately chosen to significantly reduce his/her motorhome’s tyre pressures (and this action very definitely will not have been authorised by Fiat/Peugeot) and this causes the TPMS to illuminate its warning symbol, either the owner will have to live with the symbol being constantly illuminated and the TPMS unable to warn of a ‘genuine’ pressure loss, or have the pressure-sensors reprogrammed to match the reduced pressures he/she wants to use.