hello I am looking at putting bigger tires on my truck. I just have a couple questiions. I know the tires are heavier but one thing I am not sure I understand is why larger tires make you loose MPG and or power. I mean saw the aftermarket tires are 50 lbs more per tire would the truck not run the same as say having an extra 2-300 lbs in th truck? Also this may be in the wrong forum but do you think a chip would negate the power and MPG loss of the bigger tires? Finally does anyone know if the Xcal II will allow you to change tire sizes or do you have to get the chip re-burned every time you change tire sizes? Thanks for any help.

 

Heavier tires are more rotational weight, which is different than load weight. I went from 20mpg to 17 just adding 285/70/17s on the HWY. A chip will help with power but not much with MPG.

 

I see makes sense when you think about it.

 

More weight further away from the center, double whammy. Check out Newton's Second Law.