245's are fine on 8 or 9in wide rims but the Kuhmo's aren't a true semi slick tyre.
You mentioned going to Traction Tyres, the owner Andrew is away as he is unfortunately being treated for cancer but the guys there know what they are on about and they don't rate them anywhere nearly as highly as the true semi slicks.
Falken RT615's are the same as the KU36's designed to be more a really good street tyre. You need to get a set of Falken RT215's or RS V04's if your looking for a really high performance tyre in that price range, I run RS V04's and so does Jim Richards and he has previously won Targa Tasmania on them.