Wheels and tires confuse me.... Can I get some help?

To start this off, I am driving a BMW E36 328i that has coil overs.I don't really know where to begin. I am looking at getting some new wheels and rims for my BMW, but I don't know what I can and cannot do. I Currently have 16-inch wheels with tires that are 205/55 R 16 91H. The tires are in good shape but the wheels are awful so I want to replace them. They also don't look very good.I was told I can go up to around an 18-inch wheel and I have seen people do it online. I don't know if I would want something that big but I do know I want something pretty open so that brakes and brake discs are visible. What measurements do I have to stick within for them to work?Also, if there are any measurements I still need to provide just let me know. I will try and find them!One other thing, is most of the rims that have bolts around the sides like that removable? I would repaint the wheels gunmetal gray or something like that and do rose gold bolts of they are removable. Thanks! via /r/cars http://ift.tt/2ucfkxQ