weird wear on my left side tires...

hi,
I have a 1990 Integra GS, i've had it for about a month now, and today i took the left wheel off and noticed that about on the inside part (about 1-1/2 inches) is completely bald, but the rest of the tire is fine... i looked at the back tire on the same side (left side) and it has the exact same thing. My tires on the right side are just fine, all even. but these on the left, they have this area on the inside which is completely balded. My mechanic has told me earlier that i need a rack and pinion job, my alignment is a tiny bit off, and my rotors are slightly warped (these are the problems that I know of).

anyone have any ideas as to what might be causing this?