MPG reading after recalibration

[adarkang]

I currently am running 33x12.50x15 Interco Trxus M/T’s on my 2000 4.0L SOHC. My center console computer is stating that I am getting 18.7mpg while driving on the highway. Now I know my speedometer is like 8% off so when I am going 65mph (speedometer reading) I am actually going like 70mph. I have not recalibrated, but I am curious when the computer is recalibrated should the mpg, my computer displays, increase or decrease? I am thinking it is going to go up, but I am not sure. I am strictly basing that off the fact that I am currently putting less miles on my vehicle since I have a larger diameter tire.

 

[ExplorerDMB]

Have you regeared your rear end?

-Drew

 

[je5]

It should go up by the margin of error. I would think it is reading more than 8% slow if everything else is stock. The way I like to check is to go to one of those "Measured one mile" markers on the highway and see what my odometer measures down to the tenths. The tenths over or under directly correlate to your percentage of error.

 

[adarkang]

I am not re-geared in the rear. I am running my stock 4.10s

 

[adarkang]

So then my guess is probably correct that the computer is going to read a higher mpg once I am recalibrated?

 

[X6StringerX]

I stumbled across this handy tool when I was searching to see how wide I could go on my stock wheels without rubbing. You enter your stock tire size and up to 3 or 4 other tire sizes you want to compare. It tells you how much your speedo will be off and also shows pictures of the different tire sizes in scale version. My only complaint is that they wrap the tires around a 20" wheel whether you put in you have a 15", 16", or whatever.

Click Here For The Tool

Hope that helps.

 

[adarkang]

I know how to figure out how much my speedometer is off, I am wondering how the computer calculates the miles per gallon. Will the number I am seeing for mpg currently, increase or decrease once I get it recalibrated?

 

[X6StringerX]

It will decrease.