[psy_wombats]

Are you putting gear tooth sensors on four driven wheels, two on each side, or are you putting two gear tooth sensors on two driven wheels, one on each side?

Either way, if you're trying to look to synchronize motor speeds with code, you could always try 2 PID loops for each side of the drivetrain. If you mean trying to find values for distance with many gear tooth sensors, taking the average should suffice.

I guess clarification would make it easier to answer the question.