Does the 2010 X5 and earlier have the indirect TPMS or a direct system?

When I hit a pothole and blew out a tire, it chimed and told me which tire was low. However, when I recently checked my tire pressure, all 4 tires were equally low. They were down to like 20 psi or so, if I recall correctly. I was shocked the TPMS didn't notify me that the tires were all so low, which leads me to believe it still has the older system that uses the ABS sensors to calculate the rotational speed of the tires.

Has anyone else experienced similar problems?

Thanks.

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2022 X5M Comp Dravit Grey/Full Silverstone
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2018 M5 Black/Full Silverstone
2015 X5M Donington Grey/Full Silverstone
2010 X5M Space Grey/Full Silverstone
2003 4.6is Silver/Black