y cannot leh... aiya... trust yourself... maybe the tire is old already they needto let go leh... always pls check the Manufactured date of the tire...
sure got printing on the side wall like "0109" means workweek 01 yr 09...
that size not much ppl use already... Sime... can throw grips sucks.... Silverstone so so la...
try Yokohama A Drive or Michelin XM1 if you can pay a lil more...
Toyo T1R or R1R??? i think you are aiming for peformance... how much is ur budget???
FYI Falken ST115 i heard no more...

215/45/R17
Yokohama S-Drive - RM390 Hup Shun Sunway (Dec 2008)
Falken ZIEX-912 - RM 320 Euro Zone Dataran Sunway (April09)
Hankook V12 - RM317 Tek Ming, Sunway (Apr 2009) (with trade in of your old tyres)
Dunlop Revspec - RM 330 Tek Ming, Sunway (Apr 2009) (with trade in of your old tyres)
Goodyear F1 asymmetry- RM425 inclusive rubber valve, balancing, alignment and Credit card charges, Quicksave 9/4/09
Goodyear revspec RS02(Japan)- RM 368 Quicksave (April)- other charges not included
Continental SC1 - RM 255 Euro Zone Dataran Sunway (April09)
Falken Ze 522 - RM 240 Euro Zone Dataran Sunway (April09)
Toyo C1S - RM430 (May09) ,Ed tyres S.Alam Treadwear 300,AA,A
Michelin Primacy LC - RM450per piece (free alignment + balancing) - July 09

225/45R17
Goodyear F1 ASYMMETRIC 530.00 Quicksave Subang July 2009
Yokohama S Drive 450.00 Quicksave Aug 2009
New! Toyo C1s 500.00 Quicksave Aug 2009
Continental SC3 870.00 Quicksave Aug 2009

u are towards Extreme tires... but do you mind a lil comfort as well?? if ok then you can give F1 Assy a try...
you can give Michelin PP2 a try if you don mind it is a bit expensive... but don get cheated by both PP2 and F1 Assy threads... it is quite good...
Yokohama S Drive also not bad at all... Toyo C1S is a lil on comfort as well.. Hankook V12 is more comfort but handling also not bad...