Jspec

I have a set of 245/50/17 Winterfires I got from my bosses old 740i. I wanted to get a set of cheaper rims for the winter. Is there any downfall to not using the sensors? Will the car function normally? The guy at discount tire says you have to use certain rims and the $100 rims will not work on my car. Is he full of it or telling me the truth?