I have a set of 15x7 wheels. Im looking to find out the best possible tire size for best autocrossing performance. can someone help me out here?

225/45/15 is what i would think, but i have no experience in this.

is a 205/45/15 too small?

i found a set of 225/50/15 that are very affordable.... what do u think about that size?

 

I can see a spraying coming from Stinky....
Search the forum! tire sizes have been discussed oh lets say 23 quadrillion times.

 

Not enough details, and as dirty said, this has been covered A LOT. Please search. Try "Tires" for starters and also "15x7", "225/45", "225/50" etc. There's an absurd amount of information on that topic.

 

Depends on what kind of car they're going on.