it is necessary to change the nipple on 2 wheels, oxide has formed, tell me what thread size is on the nipple?

 

the valve stem??? is it holding air? is TPMS reading?

 

Autozone, napa, o'reilly's, advance auto, etc. should have something called "tpms rebuild kit" that comes with gasket, nut, cap, and core. And if your sensor has removable valve stem then you can buy whole valve stem as well.

 

Thanks Peter!!!