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[ss134]

Hi,
I have a E90 335i LCI with 18" michelin RFT PS2s. On high speed autobahn runs the car feels unstable at high speeds. I have tried different tyre pressures with some feeling better than others. There is no pressure listed in my door or manual for over 100mph although there recommended pressure for a full load is 2.7Bar F and 3.1 R (39 & 45Psi!!).
The US manual states 2.2 Bar F and 2.5 R (32 & 36 Psi).

1.Anyone know why there is a difference between European cars and US cars, is the M Sport suspension the same?

2.Do you run higher or lower pressures on autobahn/high speed runs and what pressures are you running?

Thanks in advance for your input-this issue is seriously affecting my view of this car, any help would be greatly appreciated.

Afterthought- Please dont post up that i shouldnt be driving at high speed-i live in Germany and only drive like this when conditions and law permits.

[200Duece]

higher

[MisterSkiMask]

I would do what it says on the inside of the door regarding tire pres.

I would also consider having the alignment checked.

[ss134]

Originally Posted by 200Duece

higher

Ive been told the US states 33Psi & 41Psi normal and 32 & 36 for over 100mph.......is this wrong then?

[ss134]

Originally Posted by MisterSkiMask

I would do what it says on the inside of the door regarding tire pres.

I would also consider having the alignment checked.

There is no pressures for over 100mph on my door or in the manual.
Is it possible the alignment could be out on a brand new car?

[200Duece]

Originally Posted by ss134

Ive been told the US states 33Psi & 41Psi normal and 32 & 36 for over 100mph.......is this wrong then?

that's wrong

[200Duece]

Originally Posted by ss134

Is it possible the alignment could be out on a brand new car?

yes

[ss134]

Originally Posted by 200Duece

that's wrong

Ok thanks...what does it recommend then, like i said my car has no pressure listed for over 100mph in the door or manual.

[MisterSkiMask]

Originally Posted by ss134

Is it possible the alignment could be out on a brand new car?

Definitely.

I think they will cover alignment within the first 1000 miles or so (not positive, but I know that they won't cover it for long). The dealer will typically not want to deal with it (in my experience) and tell you that it is just following the crown in the road.

Have someone you trust drive the car at speed to see if they feel what you feel or think you feel. Then I would look into the alignment.

[ss134]

Originally Posted by MisterSkiMask

Definitely.

I think they will cover alignment within the first 1000 miles or so (not positive, but I know that they won't cover it for long). The dealer will typically not want to deal with it (in my experience) and tell you that it is just following the crown in the road.

Have someone you trust drive the car at speed to see if they feel what you feel or think you feel. Then I would look into the alignment.

Thanks for your reply-the car tracks straight and true so i had discounted alignment...it feels like its floating on the road as opposed to that planted feeling you expect from a BMW, thats why i suspect tyre pressure. The fact that theres no info for over 100mph is whats causing me problems, i dont know whether to increase or decrease the pressure and ive heard arguments for both, thats why i started this thread

[MisterSkiMask]

Originally Posted by ss134

Thanks for your reply-the car tracks straight and true so i had discounted alignment...it feels like its floating on the road as opposed to that planted feeling you expect from a BMW, thats why i suspect tyre pressure. The fact that theres no info for over 100mph is whats causing me problems, i dont know whether to increase or decrease the pressure and ive heard arguments for both, thats why i started this thread

Not to beat alignment to death, but the rear alignment could be out slightly. At lower speeds you may not notice it, and it my not be very noticeable as far as steering goes.

I would suspect that it isn't tire pressure, especially with rfts, they have very stiff sidewalls.

Good Luck.

[jopa489]

100MPH+ pressures for an E90 335 with ZSP/ZMP, running the 255/225 staggered 18" wheel/tire setup, with up to 4 passengers:

39psi (270kPa) rear
35psi (230kPa) front

Same setup with speeds under 100MPH should be:

38psi (260kPA) rear
32psi (220kPa) front

There is a nice chart on page 119 of your owners manual.

[ss134]

Originally Posted by MisterSkiMask

Not to beat alignment to death, but the rear alignment could be out slightly. At lower speeds you may not notice it, and it my not be very noticeable as far as steering goes.

I would suspect that it isn't tire pressure, especially with rfts, they have very stiff sidewalls.

Good Luck.

thanks-ill get it checked anyway. Any idea on higher or lower tyre pressures?

[ss134]

Originally Posted by jopa489

100MPH+ pressures for an E90 335 with ZSP/ZMP, running the 255/225 staggered 18" wheel/tire setup, with up to 4 passengers:

39psi (270kPa) rear
35psi (230kPa) front

Same setup with speeds under 100MPH should be:

38psi (260kPA) rear
32psi (220kPa) front

There is a nice chart on page 119 of your owners manual.

Thanks for taking the time to post this-i havent got any tyre pressure chart in my manual ive been through it several times!(maybe european manual is different?)
Are the pressures you listed for Y rated tyres as i believe they differ from the W rated?? (mine are Y)

[jopa489]

It does differ, but I gave you the values for Y-rated tires. Here's the exact page from the manual. Your car should be the second row from the bottom.

[ss134]

Originally Posted by jopa489

It does differ, but I gave you the values for Y-rated tires. Here's the exact page from the manual. Your car should be the second row from the bottom.

Thanks a lot- thats what ive been looking for! Just to confirm this for the 2009 LCI and not pre 09 cars??
I wonder why on my door it says 2.3/2.7 for below 100mph, maybe there is a different suspension set up in US cars???

[jopa489]

The manual didn't change. That's exactly what it says in my manual, and my car is also an LCI.

[ss134]

Originally Posted by jopa489

The manual didn't change. That's exactly what it says in my manual, and my car is also an LCI.

Thanks youve been a great help- i edited my last post- any ideas on the difference between US and European pressures?

[3er BMW]

Originally Posted by ss134

Thanks youve been a great help- i edited my last post- any ideas on the difference between US and European pressures?

Just go with what is stated on your door post, and you are good
for 250 km/h on the autobahn (W speed rating).

[R1200RT]

I had a stability problem with my new July 2009 E90 335d as well, so I went to the tyre shop. They new the problem and said that part of the cause was that the tyres are fairly new. It will improve when they grow older and have some wearing.
Other part was the tyre pressure which was too hig. It was changed to 2.3 front and 2.4 rear and now it is much more stable.
I have Active Front Steering, maybe that could magnify the problem?
Anyhow, I am going to try some different presures when I am in Germany again.

[ss134]

Originally Posted by R1200RT

I had a stability problem with my new July 2009 E90 335d as well, so I went to the tyre shop. They new the problem and said that part of the cause was that the tyres are fairly new. It will improve when they grow older and have some wearing.
Other part was the tyre pressure which was too hig. It was changed to 2.3 front and 2.4 rear and now it is much more stable.
I have Active Front Steering, maybe that could magnify the problem?
Anyhow, I am going to try some different presures when I am in Germany again.

Theres a few of us on this site that i know of who have this problem with the LCI. Anyone else out there?

[sokdo]

Same problem as you on my 09 e92 335i. I get this floaty feeling when I reach speeds of 80+ and don't feel very planted on the road. I have the Continental Run Flats and it's due to high pressure in the tire. Mine was around 40+.