Traveler reads different than my odometer.

[dds78910]

I filled up the R/T the other day and drove to the next town and back and the odometer was reading 118 miles which is right then I looked at my traveler to check MPG and the odometer on the traveler was about 20 miles less than the odometer in the dash. So what would cause the traveler to be that far off. And would all the other readings be off, cause I liked the MPG's it was saying I was getting.

[Xtrempickup]

tire size different than stock>?

[dds78910]

215/45/17 The overall diameter is real close to stock. 24.5 inches high I belive. I did swap out my speed sensor not to loong ago, the gear was the same color as the one that came out of the tranny.