Bigger tires and downshifting

So I went from 255x60x16 to 265x75x16 and now on my 180mile drive to work I noticed my truck downshifts on some really stupid small inclines as well as the big ones. I don't doubt that my truck may be putting out less power due to antifreeze in the gas, but this is ridiculous. I'm pretty sure I'm getting better MPG due to the larger tires, but I'm curious as to whether or not the truck will remap itself to make it more efficient and powerful with the larger tires.

Possibility or complete bullshit?

 

You might have to pull the neg lead off the battery to get the ECU to forget the old shift points.

I kinda doubt you are getting better MPGs tho....But I'd be interested to see your numbers when you get them.

 

You're overall RPM range will be lower with the larger tires.... which I'm guessing is why the truck is downshifting.

 

I do a lot of highway, so I'll get better cruising with the slightly bigger tires than I did with the smaller ones. (Although with the smaller ones my truck MOVED. Fast.

Correct, it's not much but it's still there.

 

You know what I mean you fart knocker.