Tyre pressure, parking and gravel

[Dave 123]

My mother in law has a very lovely Mini Cooper.

If the wind changes the tyre pressure warning comes on.

I’ve just taken it to the garage and pumped the tyres to the recommended settings.

Each tyre was out by 2/3 psi.

Her driveway is deep gravel. Can this uneven surface make tyres loose pressure?

She doesn’t do many miles, maybe 10 per day max, at a slow speed!

 

[Willd]

Gravel won't make any difference. They'll only loose pressure if there's a puncture, faulty valve, porous wheel etc.

Bearing in mind there's probably a 2-3 psi margin of error between diffferent gauges, have you reset the TPMS once you've pumped them up? The warning light will come at a set level, so if previously it was set to 35psi and you've only pumped them up to 32psi and not reset the TPMS, it'll still be using 35psi as it's reference... There's normally a button on the dashboard & it'll be in the manual somewhere. The sensors themselves can also fail, leading to dodgy measurements.

 

[ebikeerwidnes]

My mother in law has a very lovely Mini Cooper.

If the wind changes the tyre pressure warning comes on.

I’ve just taken it to the garage and pumped the tyres to the recommended settings.

Each tyre was out by 2/3 psi.

Her driveway is deep gravel. Can this uneven surface make tyres loose pressure?

She doesn’t do many miles, maybe 10 per day max, at a slow speed!

View attachment 746975

As far as I can tell they will flag up a problem if the pressure changes

One reason for this could be water in the tyre caused by damp air used to pump it up

hence if the water evaporates when the tyre gets hot then the pressure will increase
and then decrease again if the water condenses back into a liquid

That could maybe cause the system to think there is a problem

see if there is a reset to the pressure system

if not then monitor which tyre seems to be causing teh problem (if possible)
and ask a local garage to deflate the tyre and re-inflate it with dry air - or nitrogen if you are felling like spending a bit more

This is based on some thinking based on naff all expertise - so take it as a maybe

 

[Drago]

The gravel can be indirectly responsibly for triggering the TPMS.

F56 MINIs use a differential system.

Instead of measuring the actual pressure directly, they indirectly measure the rotation of a tyre and take a calculation from that. Thus there are no sensors.

As a tyre deflates the apparent radius chances and the wheel spins at a different rate to its companions and thus the car detects a puncture.

The F56 (had one myself until recently) has quite a sensitive system, and driving on loose gravel where the wheels don't grip the surface and roll smoothly is sufficient to trigger it. The gravel drive at my Dad's old house was enough to upset mine.

They will re-learn and reset themselves but that can take 10 to 30 miles, so if the car is only doing urban journeys I can see that might be problematic. There was a process for resetting it manually (something about a button in the glovebox, but thar might have been my old Peugeot) if my feeble memory serves.

 

[T4tomo]

alloys are susceptible to a bit of "corrosion" on the rim seal which can cause every slow leaks. Your local tyre place can check and if necessary rubdown and reseal them.

 

[Dave 123]

The gravel can be indirectly responsibly for triggering the TPMS.

F56 MINIs use a differential system.

Instead of measuring the actual pressure directly, they indirectly measure the rotation of a tyre and take a calculation from that. Thus there are no sensors.

As a tyre deflates the apparent radius chances and the wheel spins at a different rate to its companions and thus the car detects a puncture.

The F56 (had one myself until recently) has quite a sensitive system, and driving on loose gravel where the wheels don't grip the surface and roll smoothly is sufficient to trigger it. The gravel drive at my Dad's old house was enough to upset mine.

They will re-learn and reset themselves but that can take 10 to 30 miles, so if the car is only doing urban journeys I can see that might be problematic. There was a process for resetting it manually (something about a button in the glovebox, but thar might have been my old Peugeot) if my feeble memory serves.

Is my mother in laws an f56?

 

[Drago]

Yurp.

 

[fossyant]

My son's Fabia uses the ABS system to detect a deflated tyre, just like Drago's explanation - it's probably more reliable and less costly than fancy valves etc.

 

[Gunk]

F56 MINIs use a differential system.

Instead of measuring the actual pressure directly, they indirectly measure the rotation of a tyre and take a calculation from that. Thus there are no sensors.

Same as my old 330d touring, that used to throw up false alarms, especially when heavily loaded. The sensors are also easy to damage during tyre changes.

 

[Gunk]

My son's Fabia uses the ABS system to detect a deflated tyre, just like Drago's explanation - it's probably more reliable and less costly than fancy valves etc.

Most VAG group cars use this system, much less sophisticated but easier to reset and IMO more reliable.

 

[ebikeerwidnes]

I seem to remember reading in a manual at one point that the tyre pressure monitor on the car needed to be reset it the tyre was changed for a new one

It must have measured the rotation and such - and a new - and hence slightly fatter due to tread depth - tyre would knock it out and trigger warnings

not sure how you reset it - that probebly depends on the manual - or google it!

 

[fossyant]

Most VAG group cars use this system, much less sophisticated but easier to reset and IMO more reliable.

I just kick my tyres on my car, easy.

 

[Drago]

My son's Fabia uses the ABS system to detect a deflated tyre, just like Drago's explanation - it's probably more reliable and less costly than fancy valves etc.

Indeed it is, and surprisingly sensitive too.

 

[figbat]

F56 MINIs use a differential system.

Instead of measuring the actual pressure directly, they indirectly measure the rotation of a tyre and take a calculation from that. Thus there are no sensors.

MINIs use wheel sensors. It’s possible data is combined with ABS sensor readings.
https://www.ukpartsdirect.com/mini-...-sensors-set-of-4-pre-coded-ready-to-fit.html

You need to run the reset procedure when you inflate the tyres. You start the procedure and then have to drive for a while and it’ll reset itself.

 

[Drago]

Mine was diffentual sensing.

Mind you, fair point, mine was electrickery so perhaps different to ICE ones? The LC electrics had sensors.