I never answered the cracking issue. The problem is that you need to match overall circumference on the wheel, which means bigger rim equals less sidewall on the tire. The narrow sidewall means it give the rim less protection and can crack if it hits something or you drive over something in a rough manner. I am no expert by any means, but that's what my tire guys told me.
19s would certainly provide enough rubber, but you should and likely will be a bit more careful over those train tracks.
A good tire place should offer you good insight as well on this issue.