Ok, just got off the phone with the Edge tech. I am just a tad bit confused..... I have read post that state that the edge will read the PCM and transfer such info as tire size and gear ratio to the edge unit. When I purchased my vehicle the dealship had already installed aftermark rims and tires. The tires were 225/70R17. I know, small tires, they will go soon. Anyway, the speedo was correct so I asume the PCM was modified for the new tires. Since my speedo is correct, I thought the edge would read the PCM and apply the proper settings. The edge tech stated that the edge does not read the PCM and that the edge uses "general parameters". He said I would have to go to custom tune and punch in the proper information relative to tire size and gear ratio. So, which one is it? Thanks for any input.......

 

If you use the stock Edge tunes without making any custom changes the Edge uses the gear ratio value and tire size value from the PCM. If you go into custom changes you MUST enter BOTH the tire size and the correct gear ratio for your truck. The values that are in the custom area for these fields are place holders only and may not be accurate for your particular truck. That is why they must be manually entered.

 

Kd4crs, thanks for the info. I am glad to learn I was not as confused as I once thought..............

 

Also, once you input the custom values in for tire size and gear ratio, it is always best to double check everything with a GPS. You can actually get your speedometer to read closer by adjusting the custom tire size to match the speed of the GPS.