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Stephen03
08-29-2005, 03:19 PM
On stock 18inch rims....what is the ideal pounds of pressure to have the tires fill up to?

bren
08-29-2005, 04:11 PM
Check the door jamb.

NaTuReB0Y
08-29-2005, 04:44 PM
Owner's Manual :thumbup:

psi 36 front
psi 40 rear

Pinecone
08-29-2005, 05:27 PM
And then add some pressure if you prefer better handling.

Moderato
08-29-2005, 08:37 PM
I'm at 36F/37R on OEM 18's.

Disclaimer - this could change over the next 2 months.

Pinecone
08-30-2005, 05:28 AM
I run 40 - 44 all around depending on my mood. :) But pretty much never less than 40.

m3geezer
08-30-2005, 10:58 AM
I run 40 - 44 all around depending on my mood. :) But pretty much never less than 40.

I'm doing 38/44, which is the same as I used on my E39 540i with sport package. No rhyme or reason, other than it's easier for an old geezer to remember. :dunno:

On a related note, how bad a thing am I doing using a cheapo Sears compressor--you know, a $100 special that doesn't dehumidify the air? I don't have room in my garage for a big old compressor with a tank. (Have to reserve the space for auto fluid storage. :rofl: )

Moderato
08-30-2005, 09:16 PM
On a related note, how bad a thing am I doing using a cheapo Sears compressor--you know, a $100 special that doesn't dehumidify the air?

Is that really a problem? I've been using a $100 sears air compressor for inflating tires in my garage for the past year. Every time I'm done I open the air valve and leave it open so whatever moisture is in the tank will drip out. :dunno:

m3geezer
08-30-2005, 09:48 PM
Is that really a problem? I've been using a $100 sears air compressor for inflating tires in my garage for the past year. Every time I'm done I open the air valve and leave it open so whatever moisture is in the tank will drip out. :dunno:

I recall reading an article about nitrogen inflation of tires that said pretty negative things about water vapor being introduced to tires. It made points about accelerating wheel corrosion as well as creating heat build-up. It left me wondering just how bad it is to be using "wet" compressed air.

Moderato
08-30-2005, 10:04 PM
I recall reading an article about nitrogen inflation of tires that said pretty negative things about water vapor being introduced to tires. It made points about accelerating wheel corrosion as well as creating heat build-up. It left me wondering just how bad it is to be using "wet" compressed air.


Yeah that sounds bad, but if you open the air valve on your compressor when you're done and make sure there's no condensation in the tank then I don't *think* that's a problem.

spta97
09-01-2005, 07:07 AM
Yeah that sounds bad, but if you open the air valve on your compressor when you're done and make sure there's no condensation in the tank then I don't *think* that's a problem.


You should do that, but more important run the compressor BEFORE with the valve open to drain the condensation in the tank. Also, you can get in-line filters for pretty cheap. I got one but it's also got an oiler on it and I'm not sure if the oil can be completely shut off.

I am not too worried about rust on the inside of the rims, but I would be more concerned about freezing in the winter and throwing off balance of the tire. I have used a compressor for years now (33 gallon sears 6 HP) and have not had a problem. Also, the tires on the M3 are gonna last what 15 - 20k? Once they are taken off and new ones put on you can reset the clock.

There is very little water vapor in the air hose but the biggest issue is for air tools - they rust. That's why you oil them or use an auto-oiler. I would venture to think that condensation from hot / cold cycles create a fair amount of unpreventable moisture on the insides of the rims.

spta97
09-01-2005, 07:08 AM
I recall reading an article about nitrogen inflation of tires that said pretty negative things about water vapor being introduced to tires. It made points about accelerating wheel corrosion as well as creating heat build-up. It left me wondering just how bad it is to be using "wet" compressed air.

Airplanes use nitrogen because if the plane is on fire a blow out will not give it more oxygen to spread it....cool.

Moderato
09-01-2005, 04:28 PM
You should do that, but more important run the compressor BEFORE with the valve open to drain the condensation in the tank. Also, you can get in-line filters for pretty cheap. I got one but it's also got an oiler on it and I'm not sure if the oil can be completely shut off.

I am not too worried about rust on the inside of the rims, but I would be more concerned about freezing in the winter and throwing off balance of the tire. I have used a compressor for years now (33 gallon sears 6 HP) and have not had a problem. Also, the tires on the M3 are gonna last what 15 - 20k? Once they are taken off and new ones put on you can reset the clock.

There is very little water vapor in the air hose but the biggest issue is for air tools - they rust. That's why you oil them or use an auto-oiler. I would venture to think that condensation from hot / cold cycles create a fair amount of unpreventable moisture on the insides of the rims.

Thanks. :thumbup:

Pinecone
09-04-2005, 09:17 AM
Airplanes use nitrogen because if the plane is on fire a blow out will not give it more oxygen to spread it....cool.

No, they use nitrogen, becasue:

a) a nitrogen bottle is portable.

b) Airplanes use MUCH higher pressure than cars, and starting with a tank at 2500 psi helps.

c) Airplane tires generate a LOT of heat and water vapor can drive teh pressure VERY high

d) Airplane tires get VERY cold at altitude. Water vapor would condense then freeze, making the tires out of balance, not good at a 100 - 150 KNOT (115 - 172 MPH) touchdown speed.

Pinecone
09-04-2005, 09:19 AM
You should do that, but more important run the compressor BEFORE with the valve open to drain the condensation in the tank. Also, you can get in-line filters for pretty cheap. I got one but it's also got an oiler on it and I'm not sure if the oil can be completely shut off.

Those inline filters only remove condensation, ie water that has condensed into tiny droplets. You are still filling your tire with 100% relative humidity.

To reduce the moisture you can buy an inline dessicant device (I got one at Lowe's) that will remove a LOT of the water vapor. They are typically used in line before a paint gun. Water plays he11 with painting.

SteepnDeep
11-05-2007, 12:43 PM
What storage tire pressure do u guys recommend for oem 19" Michelan Pilots?

Pinecone
11-09-2007, 12:01 AM
Airplanes use nitrogen because if the plane is on fire a blow out will not give it more oxygen to spread it....cool.

NOT.

Think about it. How much air is in the tires? And only 21% of that is oxygen.

BMW_tech
11-09-2007, 12:22 AM
I recall reading an article about nitrogen inflation of tires that said pretty negative things about water vapor being introduced to tires. It made points about accelerating wheel corrosion as well as creating heat build-up. It left me wondering just how bad it is to be using "wet" compressed air.


INFORMATION

Nitrogen, an inert gas, is nothing more than dry air with the Oxygen removed. The majority of "air" already consists of Nitrogen (78% by volume). The other elements of air by volume are 21% Oxygen and 1% other gases.

All BMW approved tires have been designed and tested to deliver their expected performance when inflated with "air" and the correct tire inflation pressure is maintained on a regular basis.

The use of Nitrogen to inflate tires is not recommended for normal use of BMW vehicles; however, the use of Nitrogen is also not prohibited.

There are certain applications where Nitrogen inflation is advisable, i.e. in abnormal environment where wheel and tire overheating may occur such as in aircrafts, space shuttles, military vehicles, off-road trucks, and race cars. In these applications, the non-flammable Nitrogen can reduce the risk of fire, because Nitrogen does not support combustion and does not add fuel to the fire.

The physical properties of Nitrogen may reduce the inflation pressure loss only from the tire material natural permeability (diffusion through rubber). However, similar to air, Nitrogen can still escape from other sources of inflation pressure loss such as from wheel, wheel/tire interface, valve, and valve/wheel interface.

The most important thing for the customers is to maintain the correct tire inflation pressure on a regular basis as recommended in the Owner's Manual. Under inflated tires can reduce road holding, increase hydroplaning risk, increase road hazards sensitivity, reduce tire life, increase fuel consumption, etc.

If equipped on the vehicle, always reinitialize the Flat Tire Monitor (FTM) or reset the Tire Pressure Monitor (TPM) after the tire inflation pressure has been corrected.

E90 (3 Series)
The tire inflation pressures listed on the white tire pressure label are for maximum vehicle load and are intended for speeds above 100mph. Although this label meets US regulatory requirements and the inflation pressures are valid, setting the tire pressures according to this white label may result in a customer complaint of a harsh ride.
The yellow tire pressure label is provided as a supplement to the white tire pressure label. The yellow tire pressure label lists approved inflation pressures for vehicle use under 100mph. The tire pressures listed on the YELLOW label are the recommended pressures for optimum ride comfort.

The tire information placard is affixed to the driver's side B-pillar area of the vehicle. Please note that the tire inflation pressure listed on this new placard is for the maximum Vehicle Capacity Weight. Vehicle ride quality is harsher when the tire pressure is set for the VCW and the vehicle not fully loaded.

The Owner's Manual also provides additional tire inflation pressure information for the vehicle with occupants only and without cargo. For improved vehicle ride quality, the tire pressure may be adjusted per the information provided in the Owner's Manual.

A specific tire pressure placard is provided for each BMW approved tire size. If the customer wishes to have a different tire size than the original tire size on the vehicle, then the tire pressure placard must be replaced to match the new BMW approved tire size.

redone
11-16-2007, 03:18 PM
Living in a cold weather state, when the temperature drops, the "cold" tire pressure drops. Should I add more air to make up for this or just assume that the air in the tire will warm up anyway and reach normal pressure? Conversely, should I bleed air in the Spring?

bren
11-17-2007, 08:08 AM
Add and bleed as necessary to maintain the proper "cold" pressure.

joyofspeed
11-18-2007, 09:13 AM
Cold is defined as ambient temperature.

Fireman3
11-19-2007, 01:25 PM
Nitrogen Gas can be stored at up to 5000psi. Liquid Nitrogen is tored at an average pressure of 25psi.

BobD