Watch that scene again. They adjust both the pitch of the tires on the pavement and the timing of the "bumps" from the seams. While two different bridges could have the same timing at different speeds, or the same pitch, they're betting on the combination of pitch and "bump" timing to be unique for a given bridge and a given speed.
The pitch of which is determined in large part by the tire tread pattern, so the sound could not easily be compared / transferred between the bad guys' vehicle and the good guys' unless they knew what kinds of tires the bad guys had.
