2004 Saturn Vue Tire problems

My wife has a saturn vue red line, it has 245/50/18 tires on it. Good Year Assurance Triple Tred, 20,000 miles on them, very loud tires. When I go close to the center line, on old black top no nosie. On new black top roads they are very loud, I think it's the drivers side front tire. Tire Rack is getting a lot of bad reports on this tires. This tires have a load index of 100, 1764 # per tire, speed rating V 149 MPH, 27.7 overall dia. And 755 revs. Per mile. I want to put 17 inch tires and wheels on, 235/60/17 load index of 102, 1874 # per tire, speed rating H 130 MPH. Overall dia. Of 28.1, 744 revs. Per mile. Sears said that the 17 inch tires won't last or work. Good Year Assurance Comfor Tred Touring Tires. Thank You, Richard