Sheldon Richardson's digging in his cleats ... pleading NOT GUILTY to resisting arrest stemming from an incident where he allegedly led cops on a high speed chase in his Bentley.
Cops say the NY Jets defensive lineman was clocked at 143 MPH and blew through a red light while racing another car in St. Louis on July 14th ... with a 12-year-old child in the backseat of his ride ... with a gun in the car.
Richardson -- who's currently suspended from the Jets for a failed drug test -- was ultimately charged with resisting arrest, failure to have license plate lights, excessive speeding, running a red light and following too closely. He pled not guilty to everything.
If convicted, Richardson could face time in county jail ... plus fines. He's due back in court October 5th.