Rookie tire question

[jmatta]

First thing to do is check the date code on the fronts; it will indicate the week and year of production (WWYY format).

Reference: http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=11

If the tire is 5 years or older, it is beyond useful life and should be replaced. Plus by then it has likely turned into a hockey puck.; 23k miles on the rears...those must have been hard as rocks!