adayjk wrote:
Not only will the speedo be off, but the trans shifts will also be impacted as they are partly MPH dependant. A programmer will be required, and in the event of a powertrain failure may complicate warranty claims (meaning customer pays).
Having done this change before I can say for sure that the speedometer is not effected (at least on my dodge). Changing tire sizes does effect the speedometer though. Shift points also are not effected either. I went from 3.55 to 4.10 gears on my dodge and it made very little difference in towing other than the fact that the truck would stay in overdrive easier. I took two trips to Myrtle Beach from Michigan, the first year I had the 3.55 gears the next year I had the gears change to 4.10 and I can tell you that both trips consisted of about 2000 miles each. I always hand calculate my gas mileage and both trips worked out to 8.6mpg exactly. Point is the difference in towing performance was negligible. Try what you've got first.
