Just purchased a 2014 CTS (yesterday)
 

I gust picked up a 2014 CTS sedan luxury V-6 with 34,000 miles on it. Was checking the tire pressure today and the doorsill says it has 18" wheels, well if has 17" wheels.The Carfax build sheet says 17s. I'm thinking the door label is wrong. The tires look correct for 34,000 miles.They are Uniroyal but don't see anything to indicate they are run flat, how do I know. With no spare run flat would be a must.
New here, thanks for any help.