[Watchmaker]

I bought a new to me 2019 Screw 4 x 4 Platinum with 20,000 miles on it. I wasn't looking for a diesel but that's what came to me as the best deal. I love the truck. I didn't drive it but a few days before I put a leveling kit and better off road tires on it (Goodyear Wrangler Ultra Terrain 275/60R20). Now I know to expect a few miles per gallon difference however the lie-o-meter said I was getting 18-20 mpg for mixed driving.

So I did a gps app to test how far my odometer was actually off. (Bigger tires travel more distance per rotation of the wheel.) The result really surprised me. Now I'm mathematically challenged so correct me if my calculations are wrong.... I did a 25 mile highway test. When my odometer said I had gone 25 miles the gps said I had actually gone 33.9. To get a percentage I multiplied 25 x 4 = 100 and 33.9 x 4 = 135.6 which to me means my odometer is off by 35.6 percent. So now 19 mpg (as shown on my screen) x 1.356 = 25.764 actual mpg... right? I know I need to calculate by hand with a tank fill up but I need to know actual miles driven first....

Is this all correct? Has anyone else done a gps distance test? If not are you... will you?

Set me straight if I am wrong. Thanks for the input.

 

[wreedsvt]

I can do a test for you today or Monday.

 

[wreedsvt]

What app are you using to track Miles driven?

 

[Watchmaker]

I used Speedmeter. Thanks.

 

[getrdun]

Could you not use Forscan to revise the tire size? That may help.

 

[Watchmaker]

I had never heard of FORScan before joining this forum. That appears the direction to go. I am studding up on it now. Thank you.