Hey Paul.
I wouldn't bother using the 595 SS's on the track.
For you I would recommend using KU36's, RS-R's or AD08's if you want to spend more. In my opinion, why buy a street tyres for more money than you can buy semi's!
KU's and RS-R's are available pretty cheap through option 1 or maybe OTR. Look in the traders section of SAU.
If you wanted to spend 450-520 a tyre go for Advan AO50 or AO48 or Bridgie RE55's.
Have a go with good street's first before you go buying semi's new.
If you can stick with 17's I'd recommend that too.
Don't right off 2nd hand semi's. I did a couple of years of track work on 2nd hand stuff and they served me well. Just beware of the manufacturing date stamp. ie 3409 means 34th week of 2009. Beware semi's drive very different to streets.