Did you buy a tire/wheel package when you bought your ST? If so, no problem curb rash is covered.
If not, check with your dealer, they usually have a "Wheel Guy" that comes in and fixes this sort of thing. Generally it cost $50 to $200 per wheel depending on how bad it is.
I don't have a Tire/Wheel package on my Mustang and had one badly scuffed and 2 slightly scuffed and I paid $200 for all 3 wheels repaired at the dealer.
I made sure I had the package on the Explorer...