How to check???? Each tire is stamped when it is made!!!! So when you see tires at RV world and they are beautiful Goodyear Marathons for half price, check the date. They will be 5 years old, stamped “FB2009” meaning Feb 2009. It is totally legal to sell these but they have been warehoused for many years and the rubber gets hard and sidewalls crack. Air conditioning is bad on tires so if reported that they were stored inside..pass on this deal. RV dealers get deals when they buy a large number. Cheaper trailers all use old tires. They look great but are prone to quick wear and failure. When you get that Wazoo deal on a coach at the RV show always demand new tires if making a purchase. They will simply swap them and some sap who never reads Pippis thread will roll out with old tread. That last thing sort of rhymes. Wish the wife would take belly dancing class again. Scootertrash over and out from Borrego Springs tonight….Yuma tomorrow!!!