My Ride: 2004 545i with Sports Package. 19in wheels.

My Flat Tire warning message came on Saturday. I have Run Flat Tires (Dunlop) and couldn't tell which one of the four tires had the flat. So i took it to BMW of San Diego to have them to look at it. While I was there, there was another gentleman who also had a 2004 545 and had a same problem as I did. His flat tire monitor went off as well.

The tech checked all four of my tires and found that there wasn't a complete flat but one of the front tires was only at 28 psi. Apparently this was the case for the other guys as well.

The tech said under normal driving coniditions you expect some pressure loss over time. What surprised me was that he said Chrome Wheels are more prone to air loss. Has anybody else heard of this? Sad considering I paid more to have chrome on my car!

BTW: Both cars had same chrome rims.

I guess i have to watch my tire pressure more frequently.

Teriyaki

 

I'm not a physicist, but there is less surface tension on a chrome surface (not as porous), so perhaps the rubber doesn't adhere as well? Could also have something to do with the way chrome handles heat generated by braking, maybe it contracts more than alloy (the latter dissipates heat more quickly so perhaps remains contracted less?

 

terikayi88:
Welcome to the forum. My wife and I had identical e34 525i except her's had chrome wheels. Same model, year and tires - ok mine was a 5-speed and her's an auto - she had repeated problems with air loss. The chrome was the only factor we could identify. My .02. Once again, welcome

 

Welcome Terikay88

 

ooops I mean welcome teriyaki88

 

Duh, me too - sorry

 

Haven't heard of that problem. Anyone else with chrome wheels have it.
Btw, I have a slow leak on my right rear run flat with non-chrome wheels.

I'm taking it to the Bridgestone dealer to be checked out and try to get a new one under the tire warranty.

 

Interesting - I've never heard this. The only thing I could think of is that because of it's surface it may be more difficult to bond the tire to, and therefore more prone to leaks.

Heat expansion wouldn't explain it because you're only talking about a few thousandth's of an inch of chrome (if that much) on an aluminum wheel. The chrome is just 'along for the ride' when expansion is concerned. Plus the wheels just don't heat up that much .

 

Are you really running a 19" wheel and opted for a run-flat tire or are you simply talking about the oem 18" 545 sport wheel. Sorry to split hairs...I'm just curious...thanks

 

Just curious, trying to figure out the problem (as a metallurgist). Were the tires ever removed from the wheel in question? Is this the first time rubber was in contact with the chrome? If a tire has come off from the chrome rim, did it take some chrome with it (from off the wheel) ? If so, the chrome is peeling off from the wheel because it is stuck to the rubber and starting the leak. Aluminum and chrome have very different thermal expansion coefficients and the chrome is much stiffer than the aluminum.
Just a thought. I don't actually know if this is the reason for the problem.