BMW 320d sport Tyre pressure

[jahk86]

Sorry this is pathetic but...

Fronts 225 / 40 / R19 93Y
Rears 255 / 35 / R19 96Y

I changed from Run Flats to Non Run Flats yesterday, the tyre is exactly the same, Bridgestone Potenza S001.

After around 5 miles the Low Tyre Pressure warning came up on the I drive.

In PSI, what should the pressure actually be, I cant make sense of the door sticker.

[CanAm]

1 bar equals 14.5psi
Take it from there..

[jahk86]

I've just checked the pressure, the place that fitted the tyres has set them to 36 front, 37 rear, which I guess is too high, but 2,2 bar is around 32 which seems really low? Also why if the pressure is too high is the idrive saying "low tyre pressure"??

[dhutch]

2.2 isn't uncommon? Most guages read in bar as well as psi.

I think it works on different between wheels rather than absolute pressure, so maybe some are more than others.


Daniel

[ian in lancs]

Set the correct pressures at cold and then reset the tyre pressure warning in the idrive. Might take a couple of miles though

[jahk86]

Yeh the problem is that chart doesn't make sense to me, I don't get what the significance of the triangle and circle are? I think it should be 2,2 bar all round which is 32psi but that seems wrong

[Prinny]

This?



Triangle = front on a staggered set
Circle = rear on a staggered set.
(you can see the indicators with the car at the top...)
Therefore I think you need:

f=2.2 > 2.6
r=2.2 > 3.0
depending on load.

I’d probably go with 35psi front, 38psi rear - the 3psi over on the rear seems to suit BMW’s in my experience - all mine (335d/z4/m6/760) have had that difference on a staggered set.

HTH.

[jahk86]

if it's 2,2 that's 32psi so why are you suggesting higher?

[Prinny]

Fair point. I spend a good amount of time playing with tyre pressures when I get a car/new tyres to try and dial in the ‘feel’ I want.

Typically, on a BMW, this is around 3psi higher than their recommendation (I had a set of Falken 452’s on the 335d that needed 5psi, but I digress).

Also remember that the rear negative camber will wear inside edges quickly if under-inflated. I’m not suggesting that BMW have it wrong, more that the values they give are a range to work within, with 2.2 being the low limit point.

Finally, if you spend a good deal of time at 80+ on the Motorway, you’re likely to want a couple of extra psi in there anyway to combat the load at speed.

32 might well be fine for you, but have a play around, if you’ve a regular route, try it at a few (from cold) pressures, see if you find a difference, and then which you like best.

35/38 is a F3x guesstimate (I’ve driven plenty but don’t own one), based on my experiences.

HTH,
Rob.

[CanAm]

It's hard to read the poor image on my phone but to me it looks like Front between 2.2 and 2.6 bar and Rear between 2.4 and 3.1 bar, depending on the load.

So multiply these by 14.5 for psi depending on your usual load.

[SebringMan]

jahk86 said:

Sorry this is pathetic but...

Fronts 225 / 40 / R19 93Y
Rears 255 / 35 / R19 96Y

I changed from Run Flats to Non Run Flats yesterday, the tyre is exactly the same, Bridgestone Potenza S001.

After around 5 miles the Low Tyre Pressure warning came up on the I drive.

In PSI, what should the pressure actually be, I cant make sense of the door sticker.

32PSI is about right. Having a tyre place inflate the system to the right pressure is like asking a Python to leave a hamster alone in a cage ; it doesn't happen.

I tend to keep mine on stock pressures. Even then my Falkens wore out in the middle before the rest and that was after checking the pressures on 2 or 3 gauges.

2.2 to 2.4Bar I'd say is about right as the manual says.

Your Tyre pressure system needs resetting to account for the new pressures. The fact you have gone to non-RFTs may exaggerate the change.

Edited by SebringMan on Wednesday 24th January 08:16

[MarkJS]

I run:

Front - 35 PSI
Rear - 39 PSI