Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
I'd say that's very possible. People didn't like those 4.10 gears in the 1 tons when the speed limit was raised from 55 to 70. Someone might have found a 3.73 axle for cheap and swapped the whole axle when your originally had 4.10's. I don't a tire change would throw you off 10mph unless it was like a 4-6 inch bigger tire and you'd notice that much of a bigger tire on the truck.
I use DigiHUD Speedometer App on my phone. It has trip odometers, speed alarms, fastest speed etc and it don't work well at night, but velcro it to the dash, at night it gives a good Heads up display on the windshield. I checked it for accuracy on my GPS and my Speedo, it's always been right on the nuts accurate. Just go to Play store and search DigiHUD Speedometer.It might be easier to get yourself a GPS speedometer for 25 bucks and not worry about it.
Very True. Somewhere around here, we have a speedo calibration page with the forumula to figure out which drive gear and which driven gear you'd need in the transmission for your combination.
