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[jaqdripper]

I think the door sill and manual say 32/35, and for some ungodly reason the dealer had my tires pumped up to 43psi when delivered! I've let some air out and are currently runnin' 35 all around, but the car's handling is not to my liking. It feels a litte unbalanced during hard cornering - touch of understeer. Was wondering if there is a Mister Wizard out there who can tell me the right psi F/R for optimal accelleration and cornering.

Thanks,

Rob

[STE92VE]

Try posting this in the Tire and Wheel section. The guys over there may be able to help you.

[dougman]

Originally Posted by jaqdripper

I think the door sill and manual say 32/35, and for some ungodly reason the dealer had my tires pumped up to 43psi when delivered! I've let some air out and are currently runnin' 35 all around, but the car's handling is not to my liking. It feels a litte unbalanced during hard cornering - touch of understeer. Was wondering if there is a Mister Wizard out there who can tell me the right psi F/R for optimal accelleration and cornering.

Thanks,

Rob

You could get less understeer by dropping rear tire pressures, but since you're already at 35/35, and this is a RWD car with 50/50 weight distribution, I would not recommend it.

I would get the car out on the track and get to know its limits and really understand how it behaves, with and without the electronic stability systems. It's really difficult to get a feel for handling on public roads. If you still believe it understeers too much, you could increase the rear sway bar diameter (or decrease the front). You could also go to a non-staggered setup to balance the lateral grip capability front-to-rear.

But BMW actually has tuned these cars to be pretty neutral, and in my years in Vehicle Dynamics Development, we would have never been able to get away with the amount of oversteer you can generate on the e92, because we didn't have the electronic stability systems to save your a$$ back in the day...

You've got a 335; the best way to deal with understeer is with judicious application of the right pedal.

[jaqdripper]

Thanks D'man.

I used to race Formula Renault cars many years ago, and we used to determine presssures using a formula of roughly 10% of body weight plus f/r downforce depending on the wing settings. Obviously that's not pertainent to a street car. I've pushed my 335i to roughly 9/10ths with 35psi all around on some pretty good roads around Socal (now there's an oxymoron!) and noticed the understeer. So from your POV, maybe increse the fronts a lb. or two?

Rob

[ehhhwik]

a lot of the understeer happens because of the crappy rfts, i noticed this because i switched to "normal" tires and it took out most of my understeer that i had on my run flats

[jaqdripper]

ehhhwik - I Didn't even think about the RFTs being the culprit. This is my first experience on RFTs, and you might be right that they are the cause of the understeer I feel.

Might try to buy some track time soon and bring along a tuner buddy of mine to help sort things out to my liking. If anything, I'd rather have a bit of oversteer dialed in, though my first preference is a neutral car.



Thx.

Rob