Thanks to all who responded to my question. Just ordered the Mille Miglia 18 x 8 wheels from Tire Rack this morning at a cost of $179 each. I think I will go with the Dunlop Sport 9000 245/45ZR-18, it has a very good treadwear rating of 280. Discount Tire in Orlando quoted me a price of $1136 for four of these tires mounted and balanced out the door. After reviewing the numbers, my overall tire and wheel size will pretty much stay the same as I had with the 17's. But I will be losing about a half inch of sidewall, no big deal. Someone had asked about putting the 18's on his 98 Intrepid.
This should work as long as you keep the same or pretty close to the same tire/wheel size as before. For example, Take your 225/55/17 tire numbers, 225/25.4=8.86 inch tire width, 8.86 x .55= 4.87 inch sidewall height, 4.87 x 2=9.74, 9.74 + 17 (wheel size)=26.74 total wheel and tire diameter. If I go with the 245/45ZR-18, my overall wheel and tire diameter will be 26.68 inches which is pretty much the same as I had with the 17's. Thanks again to everyone for their input. R/T George