Tyre pressures

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Beanee687
Posts: 51
Joined: Tue Jan 28, 2020 10:22 pm

Tyre pressures

Post by Beanee687 » 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.

routemaster1
Posts: 140
Joined: Wed Mar 27, 2019 7:57 pm

Re: Tyre pressures

Post by routemaster1 » Tue Sep 15, 2020 5:12 pm

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.

Beanee687
Posts: 51
Joined: Tue Jan 28, 2020 10:22 pm

Re: Tyre pressures

Post by Beanee687 » Tue Sep 15, 2020 6:37 pm

So it's really only for puncture detection on the road.

routemaster1
Posts: 140
Joined: Wed Mar 27, 2019 7:57 pm

Re: Tyre pressures

Post by routemaster1 » Tue Sep 15, 2020 8:46 pm

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.

JohnB
Posts: 95
Joined: Fri Jun 08, 2018 3:52 pm

Re: Tyre pressures

Post by JohnB » Fri Sep 18, 2020 7:33 am

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!
C3 Aircross Flair 1.2 110 Auto with Parking & Family packs & sunroof

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