The spare does not have a sensor in it. You can swap the sensors from your current rims into the new ones. I did it a couple times already on my truck. I went ahead and got a sensor for my spare too so I don't have to deal with the light and dinger in the dash if I put the spare on the truck....
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04 Ram 2500 305/555 HO,48RE,4x4,3:73s,QC,LB,Infinity sound,MOPAR DVD,Green /Silver,Custom 4"exh,Timbrens,Bilsteins,VA C3.2,Westachs,Fumoto,BHAF,2nd gen intake,HE351,C-clamp wastegate mod,ImitationTrainHorn,16" pusher fan,ST Rims w/ Stock BFGs