found a good set of winter tires on steelies which was for a 2012 HYUNDAI VERACRUZ, the only differences are the wheel width is 7" with 35 offset and ours is 7.5" and 45 offset, tire specs matches (245/60/R18).
I can't say for sure (not familiar with Gen1 CX-9). I would do a test fit to be sure. The narrower tire will be fine, but you should also confirm that the center bore/hub size on the steelies is the same (or bigger) than the hub size on the CX-9. You also want to be sure that the calipers will clear the design of the steelies.