If your tailgate is bearing any load, over time it will happen again. Did they break before or after the tire carrier was added? My tailgate was all sorts of messed up from a 33 and aftermarket rim. I got a tire carrier that keeps it off the gate completely and the rattles are gone. Do you have a picture of your current set up?
2008 JK X, 4.10 gears, Lockers, Mopar winch bumper with a Warn 9.5ti, Mopar rear bumper, Discos, 33x12.5x17 MTZs on DC1 rims. 6 speed, Coil Spacers.