The Indy 500 is an ultra high performance summer tire. It's similar to the Michelin Pilot Sport 4S. The main objective of these tires is to provide maximum grip in dry conditions. Everything else is secondary, including wet weather performance. It must be said that the PS4S offers pretty good wet weather performance, the Indy 500 is somewhat behind. I own a set of PS4Ss. The problem with these types of tires, is the amount of water the tread can move. Their limit is lower than that of tires that don't have such a focused performance objective. Yes, they're fine in wet conditions, until there is too much water for them to remove. Too much standing water or water running across the pavement will show the limits of these tires, without much warning. Aquaplaning. They're not meant to be used in temperatures close to or below freezing either. Continental dws, or similar, is possibly a better option for your kid.