Hi Molly
You may find this of use as it specifies the recommended factory tire and rim sizes for the X Trail
Nissan X-Trail 2006 - Wheel & Tire Sizes, PCD, Offset and Rims specs - Wheel-Size.com
With regard to if Mazda or Kia rims would fit, they have the same bolt pattern, 5 or 6mm greater offset and the center bore is slightly larger so they will fit, though not quite as perfectly as a Nissan rim with 40 offset.
I had a flash that I could find you 17'' Nissan Rims but there is not much selection in that rim size in Calgary this morn. Shame because there are 3 sets of 225 55 17 Yokoham Geolandars for great prices. They are by far the best tire I have used on the X trail. Great all rounder for 3 seasons.
Which brings up my last thought, try if you can to stick with H rated tires, or T at a minimum. Anything less the sidewalls are not stiff enough and the handling and stopping is not as good.
For fun here is a list of tires I have used and tried on the X trail
1) Original Dunlops -- so so
2) Firestone off a chrysler-- pure crap got rid of after 2 weeks,
3)Michelin Hydroedge--Nice tire bought used and used for 2 years, bit of noise but not bad
4) Goodyear Assurance triple tred-- similar to hydroedge but much noisier and they are heavier tires
5) Cooper CS4-- Second best tire I have used on the X trail-- pattern is very similar to the Yokohama G95s-- sadly two roofing nails in sidewall ended those.
6) Goodyear affinity in 225 65 17 size S rated-- kept those 4 days and sold them. Awful too much sidewall, too soft, they brake well, but could kill you if you had to make an emergency swerve on the highway. Heavy and slowed the car.
7) Bought Nissan Maxima rims with 225-55-17 with V rated Toyo I forget the model at moment, simply too grippy, great taking a turn or braking but they also really prone to being affected by road surface imperfections and a desire to tramline. Mind you I hadn,t changed struts at that point.
8) Bought the Yokohamas off a 2010 Forester, and they are clearly a tire designed for an suv similar to ours. Best tire I have used on the X.