I have a W900 Kenworth 2004 3.70 axle ratio on 24.5 tires ! My speedometer is reading way too fast they set the right code in ECM but speedometer still reading incorrect right now the Speedo switches say off,off,off,on,on,off,off,off,on,on, ? It can't be corrected I'm read about 15 miles an hour to fast
Use the tire height from the ground to the top of tire (example 43 inches) not the tire size as stated on the tire.
