Tires 205/45 17 instead of stock 215 size.

Did you ask for undersized tires? This was a professional shop?

if no and yes, they slipped up, and should replace with proper size. Or just get a refund.

 

The car is OK to drive, as long as those tires stay on the same axles. Paired in the front or back of the car. Anywhere else, they're going to be a hazard. Potential emergency braking hazard, spin-out and traction control issues. Unless you specifically told the tire shop that you wanted 205/45R17's put on - the shop is liable for this. Speak to the shop owner/manager. Most chain tire stores won't deviate from OEM tire sizes, because of liability issues and require you to sign a waiver. The tire shop screwed up!!! What does our receipt say? I'd take the car back and make them fix their mistake. If those tires are on the front axle, your speedometer is going to be wrong.
If they did all four tires; it's less of an issue, but if you got different sized pairs - what are you going to do about tire rotations and spares?????

 

How are those folks going to warranty the tires they sold you? No serial numbers or tire sizes on the receipt?? I wouldn't get work done there and it doesn't sound very "Professional".

Just my 2-cents....

215/45 R17 vs 205/45 R17 Tire Size Comparison Table with Graphic Visualization