I just traded my 2015 RX 450H on a 2019 NX 300 F sport. I kept the Michelin ice radials (on steel rims) 235/65 R17.
Will they fit my NX at 225/60 R18.
I believe the bolt pattern is the same.

No, they won't fit.

Overall total diameter is 28 in +/- tread with is 8 in +/- bolt pattern same.

What am I missing? Thanks for your answer.

One set is 17 inch, and the other set is 18 inch. Unless you get the matching size wheels, otherwise 17 inch tires are not gonna mount onto 18 inch wheels, or vice versa.

AH The tires remain on their rims... snows on 17 in and summers on 18 in. So I will take off the 18 in tires on rims and put on the snows with their rims.
no tire to rim changes.

I hope I'm safe.