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Tyre pressures

Posted: Tue Sep 15, 2020 3:43 pm
by Beanee687
My car is a 2020 C3 Aircross Flair Auto 130 bhp.
I am amazed how the tyre pressures make a big difference to the ride. Now I am not talking 2 to 5 bar but 0.2 bar. Yes that small a difference.
Two days ago I thought the ride was a bit bumpy so I checked the tyres with my pressure gauge it showed that they were 2.35 in the rear and 2.4 in the front, should be 2.5 bar all round.
So as the tyres were at ambient temp I used my compressor to inflate all to 2.5 bar. Test drive proved that the ride was now much smoother.
The tyres are Bridgestone on 17 inch wheels.
In the past all my Citroen's have been on Michelin which didn't exhibit this ride change with such a small difference in pressure.
The tyre pressure monitor has to have 3 bar difference to trigger.

Re: Tyre pressures

Posted: Tue Sep 15, 2020 5:12 pm
by routemaster1
Beanee687 wrote: Tue Sep 15, 2020 3:43 pm My car is a 2020 C3 Aircross Flair Auto 130 bhp.
I am amazed how the tyre pressures make a big difference to the ride. Now I am not talking 2 to 5 bar but 0.2 bar. Yes that small a difference.
Two days ago I thought the ride was a bit bumpy so I checked the tyres with my pressure gauge it showed that they were 2.35 in the rear and 2.4 in the front, should be 2.5 bar all round.
So as the tyres were at ambient temp I used my compressor to inflate all to 2.5 bar. Test drive proved that the ride was now much smoother.
The tyres are Bridgestone on 17 inch wheels.
In the past all my Citroen's have been on Michelin which didn't exhibit this ride change with such a small difference in pressure.
The tyre pressure monitor has to have 3 bar difference to trigger.
The tyre pressure system, if it is similar to our C4 Picasso and our 2 C3s does not rally have anything to do with pressure. The way it works is that the 'system' knows how fast the wheels rotate from readings from the ABS sensors. If one of the tyres is a significantly lower pressure, the wheel rotates faster. The 'system' recognises this and gives the warning. The pressures actually don't matter. They could be 20 psi or 40 psi, as long as the system has been initialised. The pressure difference to make a warning come up is ~0.3-0.5 bar.

The important thing is that it is a dynamic system. If you drive home and park and the tyre pressure are Ok, and there is a puncture with the tyre deflating overnight, the system will not give a warning on start-up. It will only give a warning when the car has been driven a significant distance.

Re: Tyre pressures

Posted: Tue Sep 15, 2020 6:37 pm
by Beanee687
So it's really only for puncture detection on the road.

Re: Tyre pressures

Posted: Tue Sep 15, 2020 8:46 pm
by routemaster1
Beanee687 wrote: Tue Sep 15, 2020 6:37 pm So it's really only for puncture detection on the road.
Yes. It is only really any good for relatively slow punctures. It is unlikely to give a warning on a rapid deflation as it is too slow.

Re: Tyre pressures

Posted: Fri Sep 18, 2020 7:33 am
by JohnB
That seems counter-intuitive to me, i.e. usually higher pressures give a firmer ride, but I'll give it a go as mine are probably slightly under and I do find it a bit bumpy!

Re: Tyre pressures

Posted: Sun Sep 20, 2020 6:48 pm
by Sleuthey
Beanee687 wrote: Tue Sep 15, 2020 3:43 pm Now I am not talking 2 to 5 bar but 0.2 bar. Yes that small a difference.
0.2 bar is 3psi being nearly 10% of the tyres pressure.
Beanee687 wrote: Tue Sep 15, 2020 3:43 pm The tyre pressure monitor has to have 3 bar difference to trigger.
3 Bar would mean complete deflation of an over inflated tyre. Do you mean 3psi?
Beanee687 wrote: Tue Sep 15, 2020 3:43 pm I used my compressor to inflate all to 2.5 bar. Test drive proved that the ride was now much smoother.
That’s really odd. Normally higher pressure means a harder yet more economal ride as per the cars manual.

Re: Tyre pressures

Posted: Mon Sep 21, 2020 9:58 pm
by Beanee687
Possible the side walls of the Bridgestone tyres are more flexible than Michelin and need that little bit more accurate pressure in them to give right feel.

Re: Tyre pressures

Posted: Wed Sep 23, 2020 8:48 am
by Yorkshire Pud
When I picked up my Flair 1.2 I checked the tyre pressures when I got home as I noticed the ride was harder than the Captur I traded. There was between 37 and 39 psi in all the tyres. All the online tyre pressure sites advised 33 psi all round as opposed to the 36 that is advised on the car. I have set the pressure at 35psi all round and that has made the ride more comfortable.