when they woreout
tread depth gauge cost a few bucks need one maybe air gauge more important also few bucks when and how to check easy just type that into serch box most tires if good one last about 50,000 miles or longer so maybe in a couple years but alot more you need to know how to check when to check how to read wear signs what pressures to use when to rotate any tire stor e can help you but reading about can learn
