Tyre pressures for 21" setup

[CondorX5]

Amyone with advice as to best pressures for the BMW OEM 21" setup?  I have read quite a wide range of recommended pressures ranging from 32-40psi front and 36-46 psi rear. The staggered setup is 285/35R21 and 325/30R21 with the OE star-rated RFT tyres.  Have just changed the winters back to summers over the weekend and had to bin the winters as the rears had scrubbed off the inner shoulders really badly.........so I had the car on a Hunter Hawkeye machine today to discover that it was mostly out of alignment, both camber and toe.  Its all been reset now so I want to make absolutely sure the summers are inflated to optimum as they are really expensive and have to be replaced in full sets due to the quirky transfer box........thats about £1400 a time on the 21s

[NehalX5]

Best bet is to just follow the door frame pressures, they really can't be faulted as it is simply what the manufacturer recommends, especially as they are recommendations for the star marked tyres these cars are meant to have.

[CondorX5]

Trouble is, the recommended pressures lead to heavily under-inflated signs of wear on the tyres.......32psi all round does seem a tad low for the 21" staggered setup.  Lots of posts on varous forums about it.  If BMW tyre pressures are as accurate as their wheel alignment, then its not a good sign......

FWIW they seem to recommend 32psi all round for 19,20 and 21" tyres.  I tested that by drawing a chalk mark across the tread and driving a short distance and checking where the chalk had scrubbed off - sure enough, seems heavily underinflated.

[Waka]

On my 2010 40D with staggered 20" wheels I put 2.5 bar in the front and 2.7 bar in the rear (that's about 36 and 39psi).

Although I have got 7 seats and usually an 80Kg dog in the back!

[PokenH00D]

This very same thought crossed my mind couple of weeks ago.
I have the BMW 215's in 21" and when I checked the door from it said 32 psi which I thought was low given the weight of the car/size of the tyres.
When I checked the wheels for a bit more insight (new car to me) passenger side was 32 and drivers side was 36 so I was none the wiser.

[CondorX5]

I should have added mine is a seven seater, too.  But generally just one or two adults and sometimes two medium sized dogs.  I think I will try the 34/38 or close to that! combo rather than 32/32 as 32 really does not seem correct whatever the label on the B pillar states.....plus the huge rears surely need a bit more pressure than fronts?

Just wondered what others on the 21" setup were doing.