I dropped down in wheel size from the OEM 20" wheels to 18" Titan7 TS-5 wheels and called Costco in Elk Grove, CA to make sure they would install tires on wheels that are a different size than what's on the door jamb. The tire salesman/installer actually told me it was illegal to drop down in wheel size. He said it's okay to go up in wheel size, but illegal to go down in size. After he said that, I didn't want them touching my car and went to America's Tires across the street. In and out in about 35 minutes and they have their own set of jack pad adapters.