I have a set of BMW rims and on the inside of the wheel it says the size of the wheel is 17 x 7.5 with ET 41 (assuming offset?). I want to use these rims on my 545i Sport in the winter time and was wondering if this offset is too high. And if I use these, would it even fit? I plan to use 225/50/17 snow tires. Any tire/wheel expert that can answer my question would be very much appreciated. Thanks in Advance. The rim looks like this.

 

The offset of the wheel is for a 3 series. To make it work on yours you would need to use spacers of 20mm each side to bring the offset down to the 5 series level of about 20mm.
The PCD is 5/120, no matter if 3 or 5 series, so that won't be a problem. As these are probably replica wheels, make sure you correctly measure the bore of the centre hole, too, as they might have a 74,0mm hole. If that is the case, you also need hubcentric spiggot rings to make them sit snug and avoid shimmy.

If you decide to do it, on 20mm, I would go for hub mounted spacers. Better rigidity and you can use the standard bolts.

It is possible and can be done, but on a 545i, I'd rather stroll ebay and the likes and use a proper 17" E60 wheel. with so many people upgrading, I am sure you find some. Or buy a replica wheel for the winter, but use one for an E60. I also wouldn't be too happy with the rims only being 7,5 in width.

Highly personal pov , I wouldn't use them on mine and I do use non OEM replica wheels in general.

You can read up on spacers and different types, if you want, on
www.spurverbreiterung.de
although german company, the website also comes in english (I think)