[Aragorn30d]

So my car has this sticker on the door:

https://www.dropbox.com/s/plj6lscywx...14.12.jpg?dl=0

My car is equipped with 225/40r18 fronts and 255/35r18 rears.

Reading the right hand panel, it suggests 2.6 front and 2.9 rear.

However reading the left hand panel, it suggests 2.3 front and 2.5 rear.

Any clues to what its supposed to mean?

[tmarshall57]

Different speed ratings quoted in each panel. W and Y.

[Aragorn30d]

so there is! Never heard of different pressures for different speed ratings before, seems a bit weird. Especially as some tyres on the left section have different speed ratings and dont have different pressures!

I guess these pressures are also for the factory runflats, whereas mines on normal tyres, so i should add a little more pressure?

[Jeff123]

Just keep them the same as the door. For a couple of people in the car I run 39 rear and 34 front with non-runflat. That's OK for me.

[phozy888]

ahh I didnt notice this too about the pressures. I have the same size as yours 225/40/18F - 255/35/18R RFT's and always used the figures on the right - 2.6f - 2.9r .

Having checked my tyres this morning rears are 90W and fronts are 88Y all are * rated

so looking at pressure guide on the door I should be using - 2.3F and 2.9R I take it ? seem quite a difference between them 0.6 about 9psi

[Aragorn30d]

yeh its a huge varation for the speed rating change.

I was using the lower set of figures, and my tyres are Y rated, but i think i'm going to raise it up a bit, maybe 38psi all round, or 38/40.

My old car weighed a similar amount, and it ran 36 all round, albeit on 17" wheels.

I guess i'll just try it at a few different points between the two sets of numbers and see where it feels the best.

[phozy888]

yeah im gonna try 2.3f - 2.9r this weekend see how it feels. not that it feels bad now but sometimes does wonder about at high speeds possibly due to high pressure on fronts.

[tmarshall57]

Stick to door plate specifications. In most cases (except of course for ABS units, thermostats ,swirl flaps and timing chain design) BMW engineers get it right!

[phozy888]

Yeah does seem a bit weird the speed rating setup. I guess matching speed rating tyres is a must but 9 psi from my 'y' front to 'w' back does seem a lot.

[Terryk]

in my bimmer's recommended tyre pressure label, it is written sth like 2.0front & 2.3rear for unloaded vehicle...tyre size 225/45/17 W (E90 320i)
I usually prefer 2.1front and 2.5-2.6rear non runflat (but I will return to runflat tyres only on rear axle when I'll need a new pair on rear axle)

[zltm089]

38psi all round.

Fuck BMW.... I know my car!

[windymissile]

19" non RFT. 35 Fr 38 Rr.
If you go the recommended pressures for RFT on Non RFT the whole car goes 'floaty' at speed.

WM

[mob17]

Originally Posted by windymissile

19" non RFT. 35 Fr 38 Rr.
If you go the recommended pressures for RFT on Non RFT the whole car goes 'floaty' at speed.

WM

+1

I run 38front 42 rear.

[mark9661]

OK, So what would you all recommend for my E93 325i running 20's?