Hey not sure if you already purchased these but don't worry. The rims will fit perfectly fine with your existing tires.
As a matter of fact we have some 18" specials running right now for $375/set! That price is supposed to be if you are buying tires too...but I can set you up with that deal if you want to do the install and balance with us for $100.
I'll also throw in free storage for your off-season wheels
Just ask for Karl!
Rim and Tire Pro