Anyway, 18" standard wheels are fine but the xLine I'm looking at has upgraded wheels to 19" as under...

We had an extended test drive on the 18s yesterday and will drive this car on the 19s tomorrow. Does anyone have a long term experience of 19s on the New X1, and if so do you have run flat or non run flat tyres fitted?
Would 19s with standard tyres be more compliant than 18s with run flats? ...and other similar questions!
My car (the X1 is for my wife) is on 20s but I have active suspension management which makes them fine. Plus it's a sportier vehicle.
The xLine yesterday had standard seats also and we could feel they weren't very supportive in the bends. I expect the Sport seats in tomorrow's car (option) will add to a feeling of a firmer ride due to being held securely in place, but they are a must have in my opinion after 9 BMWs.
Any help appreciated. We've seen another xLine with 18s but it's almost £4k more (albeit newer), and Mineral White, which my wife prefers! (I like the Alpine, above).