I have 215 on 8" rim and it has minor tyre tuck/stretch, so don't post that 205 will be 0 tyre stretch unless your eyes are painted on and you can't see.
It is especially obvious when you have a 215 on a 7" next to a 215 on an 8".
I wouldn't go any less then a 215 on an 8" rim if your after as much grip as possible. Any less then a 215 on an 8" will cause you to have less contact tyre patch then if you were to run a 205 on a 7" rim. tyres

Semi slicks are a different ball game, this is in relation to street in general.