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      09-13-2012, 06:00 PM   #22
alynM3
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Drives: '12 JB E92
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Wow, I'm surprised that more people are misinformed about this. A lot of three piece wheels are done like this (or at least should be so that you can install TPMS easily and securely). As stated earlier, the second hole is drilled near the angled drop in the wheel (called a center drop or a drop center). The center drop is used to help mount a tire. If you have ever tried to mount a tire (or watched one being mounted) that doesnt have a deep drop it can be a real pain in the ass and you will typically see multiple techs working on the same wheel/tire to get it to seat. Anyway, the second hole allows the TPMS to sit normally as it "needs" to sit on the angled portion of the drop (as you will see in the pics that are posted) so that it isnt damaged when the tire is being seated or damaged during driving. One hole is drilled on the flat, smooth part of the barrel and one hole is drilled on the angled portion of the barrel. You use the flat, smooth part to install the air valve (which is typically a curved extended valve that extends outward toward the outer edge of the wheel). The second hole, drilled on the angle drop is for mounting the TPMS. Sometimes they use an air valve stem to do it (which isnt always ideal) and sometimes they use a nut/bolt with rubber washers very similar to the construction of an air valve stem.

As others have stated this is completely normal.

Last edited by alynM3; 09-13-2012 at 06:16 PM.