That fitment is way off for your Maxima. The dealership is correct. The tire size alone is a scarry thing. The tires you have are a little over 1.5" shorter than what you need for the car plus it is narrower than stock. The load rating would be about 300lbs per tire lower than the stock tires simply because the air chamber is too small on that tire. If it were me, I'd take everything back to the shop and demand your money back. This isn't even close to being a safe fitment. You can do some long term damage to the car running that short of a tire as well. The electronics on the car are very sensitive to changes in the O.D. and it has the same impact as changing your gear ratios on the back end of everything. The offset is totally wrong and if you are getting a vibration, I'd be willing to bet they aren't hub-centric. The wheels have to fit right on the hub and there should be no slop when you put the wheel on the hub. If the hole in the back of the wheel is larger than the hub all of the load is resting on the lugs (bad, very bad). After a few miles the lug holes will start to enlarge and you get a vibration.

There are a lot of good shops out there and there are also a lot that are more concerned with your pocketbook than your safety.