Speedo off??
 

Hey guys. I just picked up a 99 Trans Am with the LS1 and 6 speed. Mt speedo seems to be off by 12-15 MPH! I checked tire size and compared it to what's supposed to be on it and they are the same. Is there a way to calibrate the speedo electronically??? I can't figure out why it's off so much. Any help is appreciated.


Thanks

Chris