From what I understand its pretty common to need hubcentric spacers on after-market rims. Also make sure they remove the assembly washer that holds the rotor in place, a lot of rims don't have room for that like the OEM.
That said, let us know how it shakes out, those are the same rims and widths I'm planning on running so would like to know.
Hubcentric spacers or hubcentric rings? Hubcentric rings are just to fill the gap between the wheel and the hub and are there to mostly reduce vibration and possibly help balance out the wheel. They can be purchased as a set of 4 for less than $10.
If it's the rings then you'll need to know the bore diameter of the wheel.
The bore diameter of the hub on the Challengers is 71.5mm.
Just search on ebay or google "hubcentric ring 71.5mm to 'xx'mm"
If it's an actual wheel spacer then it's a different story.
Gorrilla makes a set of Hub Centric Rings, not perfect size but does make it a bit easier when mounting the wheels. As stated earlier you probably have the clips (2 per wheel) on your wheel studs which OEM accounts for but not BOSS, and DT seems to overlook that so if they are on there, that's your problem. Also Boss are Stud-Cetric which means that once yo snug/tighten the lugs it is center, a lot of folks don't bother with Centric rings, as I only added them to help keep the front 18" Boss chrome from banging against my caliper when installing them, have only about 1/8"-1/4" clearance when installed.
thanks for all the helpful information. I will mention the clips to them tomorrow. They put the hub rings on and it did make a difference. They are going to get some adapter for their balance machine to bolt all five lugs to and balance it that way tomorrow.
Thanks for the complement. They finally got them balanced correctly today. Yes they had already taken the clips off and put the hub "RINGS" in place. The manager personally balanced them and told me they were not being balanced correctly in the past. only took like 7 times balancing them to finally get it. I appreciate them keeping at it until it was done correctly, but that is way too many times to have to go back. I will not be going to Discount tire in the future.