Tow pkg don't necessarily mean 3.73 gears, "max" tow pkg does! But 285/70-17 will be just fine on your rig with 3.21 or 3.73. Spacers are a good idea so no running at full lock or articulation, and a leveling kit even better idea.
Bott line is 3.6 on the '12 and'13 can run a 285 just fine. Remember "this is your daddy's Charger motor, not your mommas caravan motor"