[Armaan]

Hi all.

Just wanted to get an opinion on what tyre pressures you run - my car label says 32 front and 35 back, but running 33 all around at the moment. These are 17’s...would you go higher on the rear tyres as recommended?

Thanks

[Brown Warrior]

I fitted a set of Goodyear Asy 2 RFT last week (19”), replacing the standard Bridgestones. The fitter told me the correct inflation pressure is 2.4 bar all round (f31 335d), i had been inflating the Bridgestones to 2.3 front and 2.6 rear

[Alscoob]

Surely BMW design their cars to run with certain pressures & tyres. If you keep the RFT why not use the recommended pressures they supply?

OK fair enough if you are experienced enough or change tyre type/ size or a track day fiend, but for the most day to day, loaded or unloaded there are specific pressures given, why ignore them? Just my opinion

[Armaan]

It’s why I posed the question, just wanted to get different points of view. My fronts are Perelli P7 RF as bmw spec, but rear tyres are Falken, so not bmw spec.

[MY340i]

I’m currently running:

[Paddy1975]

Depends on your payload TBF mate, for everyday running it is specified as same all round but if you have either passengers or heavy boot loads then more in the rear obvs, i normally run 32-33 fronts and 35 in the rear just in case and never noticed much difference on conti run flats.

[KRS_SN]

the door jamb has a pic of tyre pressure
there is a recommended pressure for 2 persons snd one for 5 persons
ive tried both and feel that the 5 person tyre pressures are to my liking
There is more steering feedback when testing the limits of traction ie i know before it loses traction.
Also it seems to handle uneven surfaces with more comfort though is slightly noisier.
One important thing is to check tyre pressure when cold or less than 2 miles of driving and fill air to recommended pressures.

[sensible]

Originally Posted by Brown Warrior

I fitted a set of Goodyear Asy 2 RFT last week (19”), replacing the standard Bridgestones. The fitter told me the correct inflation pressure is 2.4 bar all round (f31 335d), i had been inflating the Bridgestones to 2.3 front and 2.6 rear

I suspect BMW are better placed to advise on tyre pressure than the local tyre fitter.

I go with the recommended pressure of 32 front and 35 rear. I have Goodyear Eagle F1 RFT''s on 19" but it will depend on engine size and weight as to what is on the door panel.

[Brown Warrior]

I just stopped by BMW Battersea for confirmation. It seems 2.4/2.4 is correct

[un1eash]

2.2/2.4 as per spec for 18's

[Jim23k]

My 340i F31 recommends 2.2 front 2.5 rear for up to 3 passengers and I also use GY AS2 19" runflats.

For 5 passengers + full load this increases to 2.9 front 3.4 rear so it will presumably be a sliding scale of common sense between the 2 loads.

Seems to be a fair bit of variation between body style and engine though (the 6 cylinder engines will put more weight on the nose).

[Fez_7]

What about for a 320d on 398 alloys so staggered 225/45/18 front and 255/40/18 rear? I've changed to these from what came stock so my door sticker is no good.

[seenthelight!]

Also, the 2 psi extra in the back tyres actually compensates for the slightly smaller diameter between the front and back - imperative for us xdrive owners. If you stick to standard size tyres, the difference in diameter between front and back is approx 0.8% when inflated equally. inflate to an extra 2 psi at the rear and this difference is wiped out, so it can only benefit the xdrive system. As an engineer, I can confirm these figures to be correct for my 435d, and they will be ok for others on staggered setups on same profiles.
Btw, mine are front 225/40x19, rear 255/35x19, inflated to 36psi front, 38psi rear, all set from cold

[MY340i]

Originally Posted by Fez_7

What about for a 320d on 398 alloys so staggered 225/45/18 front and 255/40/18 rear? I've changed to these from what came stock so my door sticker is no good.

35 front 38 rear

[Fez_7]

Originally Posted by Barsj111

35 front 38 rear

Cheers mate. I forgot to say I'm also on runflats. Currently running 32,35 but will try this next time to see what I prefer.

[sensible]

Originally Posted by Fez_7

What about for a 320d on 398 alloys so staggered 225/45/18 front and 255/40/18 rear? I've changed to these from what came stock so my door sticker is no good.

You should still have those size tyres on the door sticker with recommended pressures. It usually caters for the majority of sizes including winter (M+S) tyres too.

This is my label but will be different from car to car.

[Armaan]

Talk about hijacked thread...lol

[Armaan]

Originally Posted by seenthelight!

Also, the 2 psi extra in the back tyres actually compensates for the slightly smaller diameter between the front and back - imperative for us xdrive owners. If you stick to standard size tyres, the difference in diameter between front and back is approx 0.8% when inflated equally. inflate to an extra 2 psi at the rear and this difference is wiped out, so it can only benefit the xdrive system. As an engineer, I can confirm these figures to be correct for my 435d, and they will be ok for others on staggered setups on same profiles.
Btw, mine are front 225/40x19, rear 255/35x19, inflated to 36psi front, 38psi rear, all set from cold

But what about those running the same tyres all round? 225 50 17...

[sensible]

Originally Posted by Armaan

But what about those running the same tyres all round? 225 50 17...

Again....isn't it on the label as shown above. (like it is on mine) Find the tyre size front and rear and then read the pressure for front and rear from the chart. So on my car that size all round would still be 32 front and 35 rear.

I have a set of winter tyres 225/45/18 (M+S) all round, so reading it from the chart it is 35 front and 41 rear.

[XK140]

To directly answer the OP...

I believe the old school view was that you first set the pressure to the manufacturer's recommended level,but if the ride/handling felt too soft or too hard for your taste then it would do no harm to vary the pressures by up to 10% either way without detriment.

For example,from 35psi you have a range of say 32 to 38psi.

I have certainly used this theory in the past,but at the moment both my cars are at recommended!

(Probably half the vehicles on the road are running a few psi out either way for one reason or another.)

[Armaan]

Thanks for your input all. For now I’ve got 33 front and 36 rear and will see how that runs. Certainly the rear feels a bit more responsive with the additional PSI, having driven a few miles at the higher pressure today.

[APJ]

Going off other threads, there are many on here that use non runflats, are the pressures different for non runflats over runflats. Do you need more pressure to compensate the slightly softer tyre walls ?, or are the pressures exactly the same ?.