I don't think the X5 still uses BMW's old flat tire monitoring system of tracking changes in rolling circumference. My 2005 545i used that system and it did not have the TPM valve stems on each wheel. Newer models now have the latter which should be able to tell the exact PSI of each tire, but BMW apparently chooses to not provide that info to the driver.

Many "lesser" makes (e.g. my Honda minivan) provide tire pressure readings.

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2008 X5 4.8i, Jet Black, Tobacco Nevada leather & just about everything else (no vent. seats, no 3rd row)