You can use the following two links to figure out what combination works best.
Based on what I can tell, your 10.5" wide wheels with +30 offset would work just fine (should be flush to the outside - might stick out an extra few mm) and only 18mm less clearance on the inside - which is not too bad.
When looking at tire sizes, you wanna look at the following things for upsizing/wider tires:
1. Tires should not stretch over the wheels ... each wheel size has a minimum tire width. My guess is for a 10.5" wide rim, min tire width would be 265 or 275. While stretch looks work on some cars, they dont' work on SUV's as it reduces functionality and rolling diameter slightly.
2. Some sizes are rare or less popular and cost more and not available in some brands. Keep this in mind.
3. Functionality and ride quality will be compromised with lower sidewall (i.e. 35) 22" wheels are probably the largest you wanna go on this vehicle but keep in mind a 35 sidewall will make it easier to scratch your rims on curbs and damage rims on potholes, not to mention you will probably feel more bumps. I have 20" rims on my M35 with 35 sidewall and ride quality is only slightly compromised and I have to watch out for potholes a lot more. My guess is that with the soft ride quality setup on the QX60, you can get away with 35 sidewall but just be wary of potholes and road bumps.
I myself am planning on getting 20" wheels that are at least 9" wide for the summer (which is specifically why I didn't want to pay for the 20" wheels from infiniti because I rather have 18" winters for cheap tires and wide 20" summers - not the skinny ones you get from Infiniti)
Good luck with your search. I like your wheel selection - I myself prefer something with more spokes, but to each his own.
Post Pics when you have them!
1010TIRES.COM - Wheel Offset Calculator