I've never heard of changing tires throwing out a CEL. Maybe its just a coincidence that it came on when it did. Did you do anything else recently to your car?
MRT 2.0 Axle-back / DT Shorties / Gutted CATS / Magnaflow X-Pipe / Roto-Fab CAI / Roto-Fab ZL1 resevoir / VMax ported TB / Elite CC / Elite brace / Pfadt Stage 2 suspension pkg. / Heritage grill / ZL1 rockers / GM lip spoiler/ HAVOC rear diffuser / COPO style hood / Hotchkis hood pins / HURST ST shifter, EMBLEMPros custom badges.