It's a kid's bike.
You and some of the other posters are WAAAYYYYY overthinking this. It's a 2 mm difference which won't mean diddly.
As for removing the stickers and polishing the rims? Go back and read the first line above again..... Besides, if the rims are anodized and you rip that away the exposed alumiunium is simply going to corrode sooner. So just stick the wheel on, call it good and let him/her go ride to exhaustion.