Am i not doing something right or what? i have 315s and i understand that its circumference but it doesn't matter what number i put in it doesn't change.

 

there are 2 mph readings if you think you have the right settings in for tire size you might be looking at wrong speed there is actual i think it is and another one
i have mine reading with in 2 mph of speedo that was reset at dodge for my 315/75/16

 

yeah im lost i guess, is that some where other than the tire size adjustments?

 

no you set the tires and then the reading for speed on the pulse you have mph and corrected miles per hour sorry had to look at the site
one of them will give you the right speed you are going or at least close to it

 

i can change both the numbers and still no change i wonder if i can fix just the spedo with my superchips tuner. would that effect anything

 

1) Set the stock tire size
2) Set the tire size for the tires you are currently running

As busta stated, you can then choose the Actual MPH, which is what the truck is actually reading
OR
Choose Corrected MPH which will be the true speed of the vehicle.

 

I changed both stock tire size and current tire size and enter it and thats it i dont see any other option .I guess I'm not seeing that. Is it supposed to be in the same menu