I have see many discussions about using metal as opposed to rubber, especially since I have the tst tpms. I have also seen some complaints of leaks, is there a make or exact type you all suggest? I am planning in switching my tires out soon. The tire shop I am buying my tires at, which is dirt cheap through a professional discount does not have metal stems. So I am planning to buy the stems, have them mount them and then run to costco for some free nitrogen. Any suggestions?