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Discussion Starter #1 (Edited)
I have the e90 330i and bridgestones..... front 32 back 36 per door panel reccomendations. I haven't gotten a chance to check them until today when I bought a tire pressure monitor and jeepers to my surprise were they off!

fr - 33.5
fl - 23.5
br - 27.5
bl - 24.5

all screwed up..... filled them to proper inflation and I could tell the car rode much better.... duh! I should have checked them right after redelivery, but dumb me put it off then slipped my mind...... just a reminder to check it if you haven't as your ride will suffer without proper inflation

my dad always told me, I would rather have a tire 5 lbs overinflated than 1lb underinflated.

I'm sure there are all different ideas people have for tire pressure set up however I usually overinflate (after checking cold) by 1lb or so.
 

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Wow, they're way off!

Why didn't the tire monitoring system sound off a warning?

Also after you've readjusted all the tire pressures, don't forget to reset the tire monitor system.
 

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While we are on the subject, I have the stock run flats on the 325xi. I noticed that tires say do not inflate over 51 lbs. The manual says to keep them at 30 lbs for normal wieght in the car. Anyone run their tires at a higher pressure than the 30 lbs reccomended in the manual? Why?

I must say that with the lower profile tires and the nasty winter pot holes (plus a post or two here where folks have bent their rims on pot holes), I'm tempted to inflate them a bit beyond 30 lbs.
 

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visor said:
Wow, they're way off!

Why didn't the tire monitoring system sound off a warning?

Also after you've readjusted all the tire pressures, don't forget to reset the tire monitor system.
It is because the warning signal when they are more than 30% off. 33.5 * 0.7 is 23.45. Or the system was initialize with these wrong tires pressure.
 

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njfred said:
While we are on the subject, I have the stock run flats on the 325xi. I noticed that tires say do not inflate over 51 lbs. The manual says to keep them at 30 lbs for normal wieght in the car. Anyone run their tires at a higher pressure than the 30 lbs reccomended in the manual? Why?

I must say that with the lower profile tires and the nasty winter pot holes (plus a post or two here where folks have bent their rims on pot holes), I'm tempted to inflate them a bit beyond 30 lbs.
Higher pressure gives you a better traction and easier to puncture the tire and bent the rim.
 

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And while you're at it, please remind the general driving populace as well. I would bet only 10% of them check their air, and because it's winter, I've seen some pretty laughable tires these days. Flat as pancakes.
 

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Good Point

Allways check pressure periodically, once a month at least, and when the tires are cold. Even if the tire is perforated and with no air it will be very difficult to tell by the eye, and the sistem will only detect the situation 4 or 5 minutes after driving at regular pace.

It will also be necesary to change the tire, even if it looks ok, if you ride it more than 100km with no air. That is because the shoulders wich are made of a diferent material (read harder) will become fatigated and the "run flat" efect compromised.

Run flats are harsher to ride than conventional tires, so try to keep pressure a little under or at nominal readings (read them in the drivers door) depending on the load of the car. If you overinflate runflats they will be much more harsher to drive than conventional tires with the same overinflation.

WARNING - Trimlining

I have noticed that runflats exhibit trimlining MUCH MORE than conventional tires. Beware of longitudinal ruts and/or grooves in the road. This is produced also because of the harder shoulders in the tire.
 

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visor said:
Wow, they're way off!

Why didn't the tire monitoring system sound off a warning?

Also after you've readjusted all the tire pressures, don't forget to reset the tire monitor system.

it'll only warn you of sudden changes, a slow leak could get much lower than that without a warning sounding.

having a TPMS doesn't mean you don't have to check pressures anymore, just like not having a dipstick doesn't mean you never have to check you oil
 

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I bought a tire pressure gauge which I now keep in the tool kit in the trunk. My pressure was a little low (3-5 pounds in each wheel) from the recommended on the door, most likely due to cold weather. I inflated my tires somewhere between the normal load recommendation and the 100mph recommendation (hey, you never know when you might do 100).

FL: 34
FR: 34
RL: 38
RR: 38

I should check it again this weekend to see how it's doing. Is Sears/Craftsman the best place to get an electric air pump?
 

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Penforhire said:
As noted, a warning at a 30% reduction is not a "monitor." That is an idiot light.

I dont' believe a 30% reduction will set the alarm off if it's a gradual leak.............
I may be wrong, but I'm pretty sure it needs to be a rapid change in pressure (to effect the abs sensors enough to trigger the light)
 

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schley said:
I have the e90 330i and bridgestones..... front 32 back 36 per door panel reccomendations. I haven't gotten a chance to check them until today when I bought a tire pressure monitor and jeepers to my surprise were they off!

fr - 33.5
fl - 23.5
br - 27.5
bl - 24.5

all screwed up..... filled them to proper inflation and I could tell the car rode much better.... duh! I should have checked them right after redelivery, but dumb me put it off then slipped my mind...... just a reminder to check it if you haven't as your ride will suffer without proper inflation

my dad always told me, I would rather have a tire 5 lbs overinflated than 1lb underinflated.

I'm sure there are all different ideas people have for tire pressure set up however I usually overinflate (after checking cold) by 1lb or so.
Tire pressure gauges, especially inexpensive ones, can be extremely inaccurate. Before I started changing the pressure, I would make damn sure that the gauge is accurate.
 

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schley said:
I have the e90 330i and bridgestones..... front 32 back 36 per door panel reccomendations. I haven't gotten a chance to check them until today when I bought a tire pressure monitor and jeepers to my surprise were they off!

fr - 33.5
fl - 23.5
br - 27.5
bl - 24.5

all screwed up..... filled them to proper inflation and I could tell the car rode much better.... duh! I should have checked them right after redelivery, but dumb me put it off then slipped my mind...... just a reminder to check it if you haven't as your ride will suffer without proper inflation

my dad always told me, I would rather have a tire 5 lbs overinflated than 1lb underinflated.

I'm sure there are all different ideas people have for tire pressure set up however I usually overinflate (after checking cold) by 1lb or so.
Manual says 33/41 for 225-45-R17 NON SP for 330i. Which is correct Door Panel or Manual?
 

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E90 is too heavy to miss the pressure, be careful guys, or you never need to high speed corner at all not to say high speed corner with passengers :p
 

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Discussion Starter #17
Jim Conway said:
Tire pressure gauges, especially inexpensive ones, can be extremely inaccurate. Before I started changing the pressure, I would make damn sure that the gauge is accurate.
so buy an expensive one to make sure the inexpensive gauge is correct? :rolleyes:

I understand what you mean, but what is the only way to make sure it is accurate besides check your pressure with a "more expensive tire gauge".

This is what I use, not sure if you would call it expensive or inexpensive :dunno: http://www.superiorcarcare.net/acstditigu.html
 

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schley said:
so buy an expensive one to make sure the inexpensive gauge is correct? :rolleyes:

I understand what you mean, but what is the only way to make sure it is accurate besides check your pressure with a "more expensive tire gauge".

This is what I use, not sure if you would call it expensive or inexpensive :dunno: http://www.superiorcarcare.net/acstditigu.html

he means those shiznitty stick type, I'm sure your gauge is fine.

I good gauge can easily be had for $20
 

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whiskey.org said:
he means those shiznitty stick type, I'm sure your gauge is fine.

I good gauge can easily be had for $20
I DID mean those stick types, which are notoriously inaccurate, but you raise a good point about how you really know. I think the best way is to try a few on the same tire at the same time. Maybe next time you're at a dealer or service station, ask to use their nice one for a minute, along with yours. If there's consensus, you can be pretty sure yours is accurate.
 

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Discussion Starter #20
wow..... I had to call my dealer the other day and mentioned my tire pressure and asked if that is one of the things that they check before delivery to the customer. He assured me it was and I told him the tire pressure I had and he said it isn't uncommon to lose 10 or even 15 lbs in a month or two during normal driving. I was curious how that could be for a brand new car? Anybody?
 
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