Blue Blurr

Hey man whats going on? My name is alex and i was reading the forums on what would be the widest tire to fit on a 10 inch rim. I have 10 inch rims and i bought some 315/30/18 michelin pilot sport ps2 thinking i had 10.5 rims. Tire rack says the minimum rim width for 315's is 10.5. Guess what im asking is are you positive they will work? I have a 2008 bullitt that i autocross, if that matters at all.