Engine/Transmission (1994 - 1998) '97 speedometer calibration

[CumminsPower98]

My cousin is ruining 265/75/16 tires, which are larger then stock for that year. Does anyone know what number of teeth the driven gear needs to be for this tire size with a 3. 54 rear? Just trying to get a number without going through all the calculatins and things. I don't even know what's in there now at this point. Thanks

 

[K5IP]

I did this because the original calibration on my 95 was off.

I measured both the speedometer and odometer over measured mile intervals on the interstate using the milage signs. I acutally measured milage several times lover 100 mile intervals. Speed can also be checked with a stopwatch or a watch with a second hand.

My original speedometer and odometer were both off (high by 8%. ) (Making my hand calculated mileage seem 8% better than real. )

My speedometer diriven gear had 15 teeth so I replaced it with one having 16 teeth.

(16-15/15=7%)

This was as close as I could get it.

Rog