Regulations... Go figure.

If all four of your tires lost air at the same rate the ABS sensor would not know that the tires were low.
Chuck

Never mind. These are style 168 made for the E53 body style :( I used this link to find match wheel styles to generations.

List of all BMW alloy wheel styles, including technical data & pictures - BMW 3-Series (E90 E92) Forum - E90Post.com

What about these wheels? Are these for a E70? The owner claims so, but I'm really new to the E70 body style :(

http://i.ebayimg.com/00/s/NjAwWDYwMA...-Pg~~48_20.JPG
http://i.ebayimg.com/00/s/NjAwWDYwMA...)8Q~~48_20.JPG

Never thought about that possibility. Great point :thumbup:

No, since there's a preset value (when resetting the TPMS) linked to the speed rotation of the tires.
(Of course, if you calibrate the system with partially inflated tires...)

So if all 4 tires lost air, all 4 would be tagged as deflated.

I had 4 lower tires on my previous X1 for winter, and until I've resetted the value on the sensors, all 4 were marked as deflated.

And no need for battery replacement in the sensors.

Almost all other markets (except the US) uses the ABS sensors.
It's not as precise and wouldn't permit to have a display of the actual tire pressure, but BMW doesn't offet this option anyway.

As for precision, you wouldn't believe how sensible this system can be to tire pressure variations.

My BMW ABS-based tire monitors did not compare the pressure to any preset, they simply compared the rotational speed of any one wheel to the average of the others. All of them could be low with no warning.

I had the experience myself with the 225/45R17 I was using on the X1 (as compared to the summer 225/50R17.
So I really don't know about yours, but all tires were tested for pressure before installing them, and they all showed as deflated.

Unless all my system was in a limbo at that time... :D


Edit:

Just had one of my friend PM'ed me about the fact that when putting back the summer tires, I didn't had to do a reset of the TPMS system, which do point out the fact that indeed, if all 4 tires were to loose the SAME amount of pressure on ALL 4 tires, it may not indicate a deflation.

DAMN !

So basically, the rest of the world, except in the US (and other places using TPMS sensors), has a not-so-precise TPMS system.
I get it ! http://www.xoutpost.com/images/smilies/bustingup.gif

For me, it did alert the 3 times I've lost pressure on a tire, which is good enough.

The tires in my E46 M3 were all a little low compared to the preset pressure during my road trip to the tail of the dragon. The tpms light lit up a few times until I filled up the tires again.

Now i think about it, the abs sensor based system actually does work quite well.

The ABS pressure sensors in my old car were pretty crappy and not nearly as accurate as the style my newer cars have had. Driving on a gravel road would set them off all the time.

I'm pretty sure that those are NOT E70 wheels...