What size tyre should i run?

[djhi]

hi guys what size tyres should i run got 2 sets of rims first size is ...
Size 17" Width 8.0 Offset 40
and the 2nd set is the stock PFL rims
any help would be awesome thinking of running semi slicks if that makes a difference cheers Djhi

 

[GLen20]

I used to have 17 x 8 +42 on my car when I got it. (Now same size but +32)
235/45/17 are a good fit and a stock Commodore size so are cheap.
Running Michelin Pilot Sport 4's @ $169 a corner. Great tyre.
Used to run Potenza RE003's
I don't know anything about semi's.