does anyone know if tire pressure monitors have to be replaced with new ones when changing tires? are they expensive and can the run of mill tire shops install them? I was thinking of replacing runflats with regular tires, would the psi still be 33lbs.?

 

You don't have to change the TPM's, and the recomended tire pressure stay's the same.

 

Do you mean the original TPM are reinstalled in new tires?

 

They stay with the rims, it doesn't matter if you change the tires.
If you change the rims, then you have to have the existing sensors installed on the new rims, or purchase new ones and have them registered by your dealer.