Don't make issue of the crack. Tell them that the crack is your problem. Tell them to fix their problem which is the peeling rims. The fact that the only way to fix the peeling problem is to replace the rim (this is not your problem). I had a similar problem in that one of my rims had rubbed the curb and had a very minor scuff. Initially they told me they would not replace the rim due to the damage. I argued that one had nothing to do with the other and they gave in and replace the rim.