You guys likely need to read the law a bit more. If you don't have AWD then you generally need specific snow tires OR chains. If you have awd you're good. If it's even more strict (which it gets in CO sometimes) then you need awd AND snow tires OR AWD and chains.

Your M wheels will suck in the snow, but i'm not sure if you'll find chains that'll fit those rears as they're super wide. Plus, wide tires are bad in the snow. Skinny snow tires are the best.

I have two sets of wheels for our X5, one is the 18" set with snow tires and the other is the M set with summer tires. Swtich them out between Nov and April.