Tpms sensors may only report when there is a problem. Which means the computer doesn't always expect them to be there, only to report when air pressure is low. Your aftermarket wheels most likely do not have tpms, but there is no tube, that is just a valve stem. There is a type of tpms that uses a normal looking valve stem, but generally not used on Lexus.
Also, the new wheels tpms would have to be programmed to be recognized.
Also a fair chance when you park, the computer reads pressures from the old wheels and tires which keeps the light off...
-cody: maintenance forum moderator
2001 Lexus IS300 - 650whp/610wtq (Virtual Dyno)PTE 6765/AEM Infinity - Auburn Sky Pearl (1 of 1348)
2007 Lexus GS450h
2010 Lexus RX350
1998 Lexus GS300 - 1jz-GTE swap
1999 Isuzu VehiCross 285/75-16 Destination MT's - Astral Silver Metallic (1 of 1021) (for sale)