Whats my REAL MPG

Stock my taco has 265/70/16 and now it has 285/75/16 with 50% tread so I took a 1/2in off when calc the final size

right now when I calc my MPG I get 17 but when add that my tires are 17% bigger I add about 3MPG so I am really getting 20MPG, is this right???

 

your math just doesn't seem right..I failed math in high school though so don't listen to me

 

bump

 

Going from 31" dia. tire to 32" dia tire gives ~3% increase in circumference. So for every mile traveled on the odometer, you've actually traveled 1.03 miles.

 

There is only a 7.3% difference in circumference between those 2 tire sizes.