I got a 98 mustang as well, I love it and I haven't had a problem yet. I wouldn't go more than 18 in the back and 17s in the front so you don't rub. You'll defiantly need low profiles but for the width in the rear I'm not sure how a 9 width would fit, it could need spacers. I was too broke to buy wheels so I just sanded mine bare and painted them with love. They've lasted a year so far with no chips. Good luck finding what you want.
1998 Bright Atlantic Cobra - 3:73's, BBK ls, Pro 5.0, 96 Cobra STB, Borla XR-1 Catback, Custom Catch Can, Spec clutch, MM Firewall adj, FRPP wires, RSD, Spoiler delete, 245/275 BF Goodrich g sports on chrome 95 cobra r's
1998 V6 Mustang : SOLD!