Speedometer Calibration

[CptnMorgan]

I have a new Tiffin Allegro Bay 35TSB on the Workhorse W24 chassis. I've notice that the speedometer is out of calibration. It registers 66 mph when the coach is traveling at 60 mph (measured by milepost timing). Can anyone tell me if the speedometer can be recalibrated? I understand that some newer vehicles with electronic speedometers can be recalibrated though the on board computer port. Is this possible on the W24?

[wa8yxm]

Your authorized service center can re-calabrate but I will ask this.

Electronic speedometers tend to be highly accurate.

Are you using the factory specified tires and are they properly inflated? Smaller (or larger) tires and under/over inflation can affect a speed-o's calibration.

Page 2: Mile posts are not layed out with a surveyor's transit as a rule, compare to a good GPS Or even a cheap one

[CptnMorgan]

Yes, they are the factory tires as delivered and properly inflated.

[oemtech]

It is done via the ECM... You need to know the tire size and the have the ECM reprogrammed. I would check it via a GPS system and if it is off then take it back to the dealer or a Workhorse Service Center.

[DriVer]

The guys at Brazel's RV Performance can recalibrate your speedometer.