Tires and wheels don't have the most effect on handling. To really make it handle look into some tubular upper and lower a-arms, lowered spindles and lowered rear suspension, stabilizer bars, urethene bushings in the suspension, frame ties and a cage to firm up the chassis, progressive rate front coil springs, good shocks with some adjustable valving, etc. The first thing you should consider to improve handling is lowering the center of gravity on the car and lowering the amount of unsprung weight.