# What tire pressure are you running? E39 SP



## Blubim (Jan 9, 2004)

Wondering what pressure people rec. for N.E. winter, sport package, E39 car with generally 2 adults, 1 infant and no or limited luggage.

Any good recs? Right now I am 39F 37R--higher than BMW recs but mostly for pothole damage prevention. Feeling some shimmy, but not sure if this is from tire pressure or perhaps wrong torque on lugs.

Bought my car CPO in Dec and while I assume the lugs are torqued correctly--it has new tires and they were balanced by the dealer--I am not sure. I don't have a torque wrench.

Anyone else have good recs? Could the slight shimmy be from the tires? They are new, so perhaps still need to be scrubbed a bit; I've only put about 400 miles on them.


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## jvr826 (Apr 22, 2002)

Blubim said:


> Wondering what pressure people rec. for N.E. winter, sport package, E39 car with generally 2 adults, 1 infant and no or limited luggage.
> 
> Any good recs? Right now I am 39F 37R--higher than BMW recs but mostly for pothole damage prevention. Feeling some shimmy, but not sure if this is from tire pressure or perhaps wrong torque on lugs.
> 
> ...


Shimmy could be caused by a few things.

1) improper balance
2) flat spotting
3) out of round tire
4) the infamous "shimmy" problem

That said, my servicing dealer does an awesome job of balancing my wheels - perfect every time.

My particular tire, Bridgestone S-03 Pole Position, flat spots a bit after sitting for a few days. It goes away after the tires come up to temperature. I wasted a bit of change when I first got them cuz I ordered a set of wheels/tires and thought they were balanced incorrectly. After having them redone by my dealer, still had the issue. I paid closer attention and noticed it went away. I also read about this on another enthusiast forum.

Doubful your brand new tires are out of round, but if they're some junko brand, i suppose it's a possibility.

And lastly, I have read about a number of people who had a shimmy that they could not get rid of. I'm unsure of the offending model year, but I'm sure if someone on this board had the problem they'd be glad to share the info.

Your thought of the lug torque is also good. Over torquing the lugs can cause brake rotor warping, and a shimmy. I have also read that improper torque could contribute to the infamous shimmy problem. As I recall, originally the torque spec was 77 lb-ft and was upgraded to 88 lb-ft. I have aftermarket wheels and use the 88 lb-ft spec for mine. IMO, if I were you I'd invest in a nice torque wrench and check up on the settings now and then.

Your pressures seem OK - I run 36psi all around after experimenting with many combinations. I find this setup the most comfortable (i have 18" setup) and great handling. 33psi is too low for this setup up front and 41psi is way too high for the rear setting. I tried moving up to 38psi all around and didn't care for it too much. Your best bet is experimenting and finding the setting(s) that work best for you and your particular tire. Start with the factory spec and move up/down until you find a good balance of comfort and ride, as well as even wear. Also be sure to check the pressure when the tires are cold, before the first drive of the day is always a good time to do it. Adjust the pressure above the desired setting, then let air out to reach the desired setting.

Someone once gave me a word of advice on tire pressures related to my motorcycle. He told me to be sure to check the pressures throughout a day of riding in hot weather. Heat has an incredible effect on tire pressure. I have found that a properly adjusted tire at 8am can easily exceed the maximum allowable setting (by 10 or more psi) by lunchtime- opening the door to danger in a hurry. Car tires don't fluctuate as much, but the same thing could happen there too.


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## DSPTurtle (Oct 4, 2003)

I run 40fr/39rear and torque to 90ftlbs.
Is your shimmy under cruise condition or does it just happen when braking from 50-60mph?
JB


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## Tahoe (Jan 9, 2004)

jvr530i said:


> Someone once gave me a word of advice on tire pressures related to my motorcycle. He told me to be sure to check the pressures throughout a day of riding in hot weather. Heat has an incredible effect on tire pressure. I have found that a properly adjusted tire at 8am can easily exceed the maximum allowable setting (by 10 or more psi) by lunchtime- opening the door to danger in a hurry. Car tires don't fluctuate as much, but the same thing could happen there too.


On that subject, I read that you will get a 1 psi difference for each 10 degrees of ambient temp change. Also 1 psi for each 1000 ft of elevation change. 
So if you start on the warm coast and drive up to the cold mountians you're okay.


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## Blubim (Jan 9, 2004)

DSPTurtle said:


> I run 40fr/39rear and torque to 90ftlbs.
> Is your shimmy under cruise condition or does it just happen when braking from 50-60mph?
> JB


Shimmy is while cruising on the highway. Very slight but still noticeable. Have not noticed it when braking but I will be on the lookout next time I am in the car.


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