Tire pressures when towing

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Nov 16, 2015
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Jul 18, 2017
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I’m totally lost now.
Thought is was a simple explanation for a man of your standing. On some cars the sensor is paired in a specific order so if the sensor is moved to another position it gives false reading for the tyre.
For example as I stated you move a front of side to the rear offside, it is reading the rear offside but is showing that it is still the front offside hence the need to re-pair the sensors.
Does not apply to all cars and if that is the case with BB's car I am surprised as most modern cars do it automatically now.
 
Nov 11, 2009
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Thought is was a simple explanation for a man of your standing. On some cars the sensor is paired in a specific order so if the sensor is moved to another position it gives false reading for the tyre.
For example as I stated you move a front of side to the rear offside, it is reading the rear offside but is showing that it is still the front offside hence the need to re-pair the sensors.
Does not apply to all cars and if that is the case with BB's car I am surprised as most modern cars do it automatically now.
Since my first car in 2010 with TPMS none have required matching to a position even though as 4wd the cars would have their wheels moved back to front etc.

My Subaru TPMS has three settings P1-3 aligned with solo, loaded or towing. The Rio just has a TPMS button. All I’ve ever had to do is press a button when I’ve adjusted tyre pressures. Easy even for someone “ of standing” whatever is meant by that phrase.
 
Jul 19, 2021
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The TPMS on our old Tiguan was pretty rubbish, tyre could use 10psi and still not register any warning, but pump it back up and it would alarm.
Was pretty easy to reset though, just go into the menu , scroll to tyre pressure reset and then hold down the button for a few seconds.
 
Jun 16, 2020
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I’m totally lost now.
My understanding of what Buckman says is. Each wheel has a sensor, the car recognises the 4 sensors and attributes a wheel location to each. If wheels are swapped the car needs updating. Otherwise it is reporting faults from the wrong wheels.

My car does not have fitted tpms. But in the past I have had valve mounted systems. With them, if a wheel is swapped, either the receiver needs updating, or the senders need fitting in the original location.

John
 
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Nov 11, 2009
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My understanding of what Buckman says is. Each wheel has a sensor, the car recognises the 4 sensors and attributes a wheel location to each. If wheels are swapped the car needs updating. Otherwise it is reporting faults from the wrong wheels.

My car does not have fitted tpms. But in the past I have had valve mounted systems. With them, if a wheel is swapped, either the receiver needs updating, or the senders need fitting in the original location.

John
None of mine have ever required position resetting. Anyway Buckman clarified his post in #53 above.
 
Nov 6, 2005
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My understanding of what Buckman says is. Each wheel has a sensor, the car recognises the 4 sensors and attributes a wheel location to each. If wheels are swapped the car needs updating. Otherwise it is reporting faults from the wrong wheels.

My car does not have fitted tpms. But in the past I have had valve mounted systems. With them, if a wheel is swapped, either the receiver needs updating, or the senders need fitting in the original location.

John
Some cars have a TPMS sensor in each wheel arch - so swapping wheels/tyres around is reflected automatically on the dashboard display.
 
Jun 16, 2020
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Some cars have a TPMS sensor in each wheel arch - so swapping wheels/tyres around is reflected automatically on the dashboard display.
I was not aware of that. As I said, my car does not have fitted tpms. But in situations like you say, it would be automatic. I wonder if that is the norm or just some cars.


John
 
Jan 3, 2012
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What do you mean “ reset” at VW dealer? I really cannot understand why a dealership have to be involved in tyre pressures.
i cannot get down with my mobility and my dealership said if i need anything just ask so i did they pump my tyres for towing and i took it yesterday and it sorted now . and left them some feedback great service .
 

Sam Vimes

Moderator
Sep 7, 2020
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Like many things there is not a 'One size fits all' solution.

I've just got the first car with TPMS. So far I've only read the manual.

It needs to be reset if the tires are changed or rotated. It also needs to be reset if the pressures are adjusted i.e towing vs non-towing.

Target pressures are set per wheel and used to generate a warning if not met.

There is also a need to recalibrate the system after a pressure change as the system also incorperates temperature sensing.

The TPMS system reports the pressure per wheel graphically so the sensors need to be assigned to the specific wheel positions, although I'm not sure how this is works but the manual states:-

Procedure:
1. Change tyre position or have new TPMS sensor
fitted.
2. Park with Ignition ON or Engine ON for more
than 20 minutes. You must perform this step before
driving.
3. Drive the vehicle for several minutes between 25
km/h (16 MPH) and 100 km/h (64 MPH). The
TPMS sensor ID and position will automatically
be detected.
 
Nov 11, 2009
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i cannot get down with my mobility and my dealership said if i need anything just ask so i did they pump my tyres for towing and i took it yesterday and it sorted now . and left them some feedback great service .
With a dealership as good as that I guess you will be with VW for a long time to come.
 
Nov 11, 2009
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Like many things there is not a 'One size fits all' solution.

I've just got the first car with TPMS. So far I've only read the manual.

It needs to be reset if the tires are changed or rotated. It also needs to be reset if the pressures are adjusted i.e towing vs non-towing.

Target pressures are set per wheel and used to generate a warning if not met.

There is also a need to recalibrate the system after a pressure change as the system also incorperates temperature sensing.

The TPMS system reports the pressure per wheel graphically so the sensors need to be assigned to the specific wheel positions, although I'm not sure how this is works but the manual states:-

Procedure:
1. Change tyre position or have new TPMS sensor
fitted.
2. Park with Ignition ON or Engine ON for more
than 20 minutes. You must perform this step before
driving.
3. Drive the vehicle for several minutes between 25
km/h (16 MPH) and 100 km/h (64 MPH). The
TPMS sensor ID and position will automatically
be detected.
Step 2 seems an overly long time. I don’t like just leaving the ignition on without a running engine except for short periods when doing menu changes. But 20 minutes !!!!!
 
Nov 11, 2009
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Looks like they do need resetting each time the pressures are adjusted.
Thankfully my Santa Fe doesn't.
Reset can mean two things. One when you adjust or pump up the tyres, the other if a wheel changes location. The five cars I have had with TPMS all I have done when tyre pressures are up or down is to either press the TPMS button, or in the case if our Rio go into a settings menu and click on set.
 
Nov 6, 2005
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Looks like they do need resetting each time the pressures are adjusted.
Thankfully my Santa Fe doesn't.
I guess there's a lot of different systems out there - my Touareg doesn't need a TPMS reset - it only detects low pressure so will set the alarm off if they drop below normal level.

I do find the TPMS display useful to see the pressure increase during a journey - if it increases more than 0.3 bar, it indicates that the cold setting was too low to start with.
 
Mar 14, 2005
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Yes there are several different ways in which tyre pressure can be monitored.

Some directly measure the pressure with a sensor which has to be attached to the wheel, and because it rotates with the wheel it has to wirelessly transmits the reading to the cars tyre pressure center.

These systems compare the readings to a value stored in the system and will alert when the reading exceeds a pre defined deviation. Some of these systems may also compensate for temperature changes. Batteries may need to be periodically changed

Others use a dust cap sensor which is chosen to match your minimum pressure. It will broadcast an error signal to the controller if the pressure falls below its set value. If you need to reduce you tyres operating pressure below the sensors set value you will need to select different dust caps set to the desired value.
Batteries may need to be periodically changed

My present car is the only one I have experienced with TPMS, and it uses the cars ABS system sensors.

To set it, the tyres must be first inflated to the desired pressure, and the car driven. Using the steering wheel's position sensor to know when it's driving dead ahead, it compares the the pulse rates from the ABS sensors, and notes their values. Subsequently if the ratio of the pulses from the wheels changes it suggests the one that has disproportionately increased has lost pressure.
 
Oct 3, 2013
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To some extent you're correct except that the rating plate on my current car has no mention of what to do when towing.

As I mentioned previously the new car hasn't arrived yet but I'd bet the rating plate doesn't mention what to use when towing. I'll be happy to be proved wrong though.
Don't think any car instruction manual would specifically mention towing,my car manual talks about heavy loading which a hitched caravan would impose on the car.
 
Jun 20, 2005
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The manual in most cases details the Maximum braked and Un braked trailer weights. In regard to tyre pressures I think we may be beating ourselves up . It is based on the maximum load anticipated on the front and rear axles IMO that takes into account full passengers , boot and permissible max trailer nose load .Hence the two ratings on the plate
 

Sam Vimes

Moderator
Sep 7, 2020
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499
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Don't think any car instruction manual would specifically mention towing,my car manual talks about heavy loading which a hitched caravan would impose on the car.
One of the manuals I download which is not for our region goes into quite a bit about maximum load limits but only for Australia. I did find some information on my V5 document concerning Mass in Service and Braked and Unbraked towiing limits.

For Australia...

CAUTION
While towing a trailer, check the engine coolant
temperature gauge regularly to prevent engine
overheating.

1659948268298.png

jA Tongue load
jB Total trailer load
jC Less than 10%
MAXIMUM LOAD LIMITS (for Australia)
Maximum trailer loads (including tyres and other
loaded equipment):
1) Never allow the total trailer load to exceed:

1659948370269.png
2) The total trailer load must be lower than the following
three values, even if it does not exceed
the maximum permissible trailer load:
• Towing capacity displayed on a tow-bar.
• Trailer’s gross vehicle mass marked on a
coupling body.
• Gross vehicle mass marked on a trailer data
plate.

The maximum trailer load that can be towed by your
vehicle depends on the towing equipment fitted to
the vehicle. Therefore, it is important to not only
have the correct equipment fitted, but also to use it
correctly. Towing loads greater than the value specified
for your vehicle or using towing equipment that
is not provided by NISSAN could seriously affect
the handling and/or performance of your vehicle.

Vehicle damage resulting from improper towing procedures
is not covered by NISSAN warranties. Information
on trailer towing and the required equipment
should be obtained from a NISSAN dealer or
qualified workshop.

1659948409704.png
Maximum rear gross axle weight
The rear gross axle weight must not exceed the
Gross Axle Weight Rating (GAWR).

Engine – Transmission Axle GAWR
R9M – CVT 2WD 1015 kg
MR20DD – 6MT 2WD 985 kg
MR20DD – CVT 2WD 1000 kg

The trailer must be loaded so that heavy goods are
placed over the axle.

Maximum tongue load
Never allow the tongue load to exceed 10% of the
total trailer load. If the tongue load exceeds 10%,
rearrange the cargo in the trailer.
 

Sam Vimes

Moderator
Sep 7, 2020
813
499
2,135
Returning to TPMS systems. When I've had tires replaced I usually get the valves replaced as well. With the TPMS system do you keep the valves or get new ones? If new do they have to be OEM versions?
 
Nov 11, 2009
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Returning to TPMS systems. When I've had tires replaced I usually get the valves replaced as well. With the TPMS system do you keep the valves or get new ones? If new do they have to be OEM versions?
My TPMS sensors are independent of the valves and it’s good practice to change valves when tyres are replaced or even repaired. I couldn’t recognise an OEM valve if it reared up and kicked me.
 
Mar 14, 2005
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Whilst it may be of academic interest to see how other political systems might legislate and define towing requirements, foreign systems should not be assumed to be acceptable in any other country. There may be some allowance for temporary visitors to use approved foreign systems for a short defined period of time, but for the long run or permanent domicility all local towing protocols should be fully adhered to. Always check the destinations towing law requirements before entering a foreign area.

Regardless of where you are across the globe, the mechanical challenges of towing center axle counter balanced trailers will have similar causes and effects, so the real need for good loading and outfit matching applies everywhere, but local laws and limits vary as might any advisory information.

The Australian system depicted above by Sam, uses different names and acronyms compared the the UK for parts of the outfit, and apparently the advisory values for tongue weight (Nose Load) also differ to the UK.

I am impressed with diagrammes they use as I think it shows detail of how some of the criteria should be measured. Based on many comments here in the forum its clear how some criteria are not fully understood, and that can easily lead to incorrect loading, and an illegal outfit.
 
Nov 11, 2009
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I’ve just been to my granddaughters to check her car out as she has her driving test this afternoon. The makers label on the nearside B pillar gives pressures for front, rear for three conditions. Solo, loaded and towing. But her manual just gives noseweight but says nothing about the interaction of load and towing hitch loading. But since she doesn’t plan on towing it’s not a problem for her. My feeling is that most families would just load up the car and then put the 75 kg noseweight or whatever and drive off into the sunset. Practically who is going to measure axle loads, apart from this anorak.
 

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