max wheel size for 2000 camry

I have a 2000 camry that needs new tires so i want to upgrade and get new wheels. I'm planning on lowering the car about an inch and want to know what size of wheels I should get. So far all the tire shops I've talked to have said that 18's are the biggest that they would put on even with a low pro tire. Anyone have any advice?

18 is the biggest we've test fitted for your car.