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Who should you trust? Citroen's or your tyre supplier's recommendations?
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Stealth   
Wed Jan 02 2013, 03:32am
Joined: Aug 11 2012
Member No: #986
Location: Sydney
 Seems to me the answer should be Citroen, however...

My Australian delivered 2009 2.7Hdi (November 07 build) has the below label inside the driver's door. It recommends 35psi (front) and 26psi (rear) and seems different from the style of label shown in the 'everyday running' section of C6 Owners. I interpret the label to mean that these tyre pressures are required, regardless of load.

The 26psi (rear) 'official' recommendation seems a fair bit lower than the pressures being discussed in a couple of the forum posts I found. It also seems surprisingly low for a car of the C6's weight. I'm wondering if anybody has a clue why the Australian (and I presume New Zealand) variant has a rear pressure recommendation so much lower than UK/Euro variants?

I replaced my tyres 3,000 kms ago and the supplier inflated all four tyres to 37psi. Having just discovered this (digital pressure monitor - Xmas gift), I deflated the rears to 26 and the fronts to 35.

Anticipating the pressure sensor warning alerts, I started up and was immediately greeted with 'SERVICE' and tyre pressure alerts on all four wheels. After about a 10 minute drive, the pressure monitor display indicated the sensors were recalibrating and the warning was lifted from both front wheels (green) however the rears returned (red) warnings again.

After stopping and leaving the car for 30 minutes, on the next leg of my journey the display indicated two greens (front) and two reds (rear). More audible alerts as well, of course.

So, the Six seemed quite happy to accept 35psi as the new pressure on the front tyres (could the 6 be clever enough to figure out that two fronts, adjusted to identical pressures, means deliberate choice?) but it seemed to refuse to accept the idea of 26psi in the rear tyres as a rational choice - preferring, perhaps, to assume a madman was at the wheel!

Anyway, convinced by the multiple warnings and alerts that I must be crazy to observe the label and put 26psi in the rears, I quickly returned all four tyres to 36psi. After re-starting, four greens displayed once again, so happy days!

Now, a few facts. I'm not running the factory fitted Michelins but am trying Bridgestone Turanzas 245/45R18 as an alternative. I'm not sure whether the Citroen recommended pressure on the sticker in the door (obviously intended for Michelin tyres) would be greatly different if Citroen were making the recommendation for Bridgestone tyres (but 10psi would be a huge difference no?).

    Should I trust Citroen's pressure recommendations on the label in my door?
      Should I trust my tyre dealer who says 36psi all round is best to minimise wear? (and that manufacturers recommend the most comfortable ride settings - not those that are optimised for long wear)
        or, should I consult Bridgestone about its recommendations?

        Any advice or clues on the reason behind the different specs would be appreciated. I'm not concerned, just curious.
        C6Dave   
        Wed Jan 02 2013, 07:36am

        Joined: Oct 01 2009
        Member No: #1
        Location: Northumberland
        		 I have no idea why UK cars should be any different to anywhere else in the world and ran both my 2.7 and the current 3.0 6's at 2.4 Bar (35 psi)all around as there are only the two of us in the car.

        I forget for the moment what the lower range setting of the TPS system actually is, but think it's in the region of 30 PSi, below which the system will throw an error message.
        Website
        gmerry   
        Wed Jan 02 2013, 09:38am
        Joined: Dec 11 2009
        Member No: #21
        Location: Scotland
        		 Stealth, I run my non Michelin tyres at factory setting on the fronts and 0.2 bar lower on the rear (better balance and less centre wear on the rear tyres) unless fully loaded AND high speed in which case I increase the pressures to the factory recommended high speed setting.

        And it all works fine with the in-built factory tyre pressure monitoring systems.

        Regards
        G
        Gobxoy   
        Wed Jan 02 2013, 10:29am
        Joined: Jan 20 2012
        Member No: #786
        Location: Essex
        		 TPMS only are required to give the warning signal at 25% below the manufactures settings. popular mechanics did an article about TPMS - Click Here -

        Simperit do a PDF - Click Here - page 40 gives this chart Pressure vs weight, but you also should see the section on speed etc. Sorry I haven't time to look at this more for now, it does give an idea though.



        Tjensen   
        Wed Jan 02 2013, 12:41pm
        Joined: Jul 17 2012
        Member No: #954
        Location: Bergen
        		 Interesting. The "strange" recommendadtion 35 front and 26 back is logical from the perspective of tyre size and weight distribution. If I remember right the SM and DS also had this difference. But usually manufacturers will tune the angels etc to accept same size/same pressure
        Stealth   
        Wed Jan 02 2013, 04:45pm
        Joined: Aug 11 2012
        Member No: #986
        Location: Sydney
        		 Thanks for your replies everyone, especially the link to the Popular Mechanics article Gobxoy -very interesting how TPMS systems work. I think I'll stick with 35 all round for the time being.
        James   
        Wed Jan 02 2013, 09:26pm
        Joined: Mar 03 2012
        Member No: #817
        Location: Somewhere in the south of England
        		 One odd point is that sticker doesn't look the same as the ones I've had in my last few citroens, next tot the one with the orga number on. Looking at the photo it doesn't look like it's in the door shut. (Just out of curiosity - do these stickers change sides with LHD / RHD vehicles ? Or do LHD have the sticker on the kerb side / fuel cap side)

        For starters mine shows two pressures for loaded unloaded. And I think the pressure sensors trip at about 2.0 bar / 30 PSI (per Dave) - even legal requirements only say they need to trip at a lower pressure (per gobxoy)
        Stealth   
        Wed Jan 02 2013, 11:30pm
        Joined: Aug 11 2012
        Member No: #986
        Location: Sydney
        		 Hi James,

        You're right. The sticker does look different from other Citroens. My C4 had a sticker almost identical to the one I've shown below (screen grab from day to day running section).

        The sticker is affixed in the driver's side door sill (B pillar) so yes, they do move it from LHS to RHS for RHD markets it would seem - but my sticker is completely different and doesn't offer normal or heavy load pressures.

        Weird. Must ask the dealer next time I see him.
        Gobxoy   
        Thu Jan 03 2013, 09:47am
        Joined: Jan 20 2012
        Member No: #786
        Location: Essex
        		 This is what it looks like on mine I think it should be the same on 2.7 as the unladen weight is within a few kilos. If you have a Citroën dealer near you you could look to see what other Citroën have. One up I'm guessing 1200 Kilos across the front axle and about 770 Kilos across the back 35psi and 26psi doesn't seem out of the way, but doing the shopping loads the boot which is aft of the back axle so I think a little investigation is required. Have you aske Citroën Australia to confirm? If they are any thing like UK should only take half adozen phone calls and e-mail follow ups.

        Hawkie   
        Thu Jan 03 2013, 12:02pm
        Joined: Feb 01 2010
        Member No: #45
        Location: Stockholm
        Gobxoy wrote ...

        This is what it looks like on mine

        I have the same sticker on mine... but with another orga-number
        Stealth   
        Thu Jan 03 2013, 09:59pm
        Joined: Aug 11 2012
        Member No: #986
        Location: Sydney
        Gobxoy wrote ...

        Have you aske Citroën Australia to confirm? If they are any thing like UK should only take half adozen phone calls and e-mail follow ups.


        Thanks Gobxoy, no I haven't asked Citroen Australia yet but I think I'll just approach my dealer first. I'll shoot him an email today but a lot of Australian businesses are closed over this first week of the new year.

        It will be interesting to see what he recommends.
        smihaialex   
        Fri Jan 04 2013, 04:28pm
        Joined: Sep 18 2012
        Member No: #1031
        Location: Bucharest
        		 There is absolutely no doubt about this... If you use your C6 normally (meaning regularly reaching speeds of over 100 Km/h - 62 mph and carrying some luggage and more than one passenger), then all of your tyres should be @ 37-38 psi, the equivalent of 2.6 bar.

        So in this case, your tyre guy was absolutely spot on...

        Thank you,
        Sam
        Stealth   
        Sat Jan 05 2013, 03:06am
        Joined: Aug 11 2012
        Member No: #986
        Location: Sydney
        		 Thanks Sam,

        That's pretty much my type of driving.
        smihaialex   
        Sat Jan 05 2013, 02:00pm
        Joined: Sep 18 2012
        Member No: #1031
        Location: Bucharest
        		 My pleasure!

        Sam
        ul9601   
        Sat Aug 27 2016, 04:58am
        Joined: Dec 14 2014
        Member No: #1975
        Location: Auckland
        		 I realise this thread is more than 3 years old, but I have the exactly same problem with mine.
        One day, the TPMS gave a low pressure warning message, so I pumped it up and gave a bit more air on the other three as well, until the deflated one didn't cause the warning message, as I didn't have a gauge handy.
        This morning, I hooked up the gauge and bled air out to 35 f & 26 r psi as the sticker instructed - when I went for a drive, it went into re-initialise mode, which kind of made me a bit uneasy and subsequently threw low pressure warning on both rears. I did think the figure for the rear was a bit on the low side, but hey I thought there must be a good reason for it. I have the exact same sticker as Stealth's, at the same location.
        So do the rest of NZ/AUS new cars have this problem also?
        In the mean time, I'd better pump it back up to 35 psi minimum.
        Cheers,
        Sam
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