Tire and fit question, stock rim

Hi guys.. A quick question:

I have the stock 17 rims on (17 x 7 I believe) my IS and I am replacing my 215/45 s with winter tires..

Now by one method or another, the tires I got from Tire Rack are the wrong size (I don't want to get into that now, I'm pretty upset considering I drove to another state (they were delivered to my parents) to get them installed only to find out they were the wrong size).. I still don't understand what happened but I will call them tomorrow first thing.

Anyway, what I got was 205/50 s .. Now the question is, can I mount the 205/50 safetly on my rims ? I talked to NTB, and they said no problem.. But I talked to another place, and they wouldn't have anything to do with it saying that you cannot SAFETLY put a NARROWER tire on your rims than the stock tires.. I will call Lexus tomorrow, but I trust you guys more than my local dealer..

So can I safetly replace my 215/45 with 205/50 ?? I really don't want to have to go through the pain in the *** of trying to return these, pay for shipping *3* times (original, return, and replacement set) if I don't have to..

Whats your advice ??

Thanks all

issed:
AbsoluteIS