Larger Tire And Fuel Milage ?

[BIG CAT]

Ok everyone im new here and this is my first post. I have a 2009 GMC z71 with stock 265/75/17 tires im wanting to put a 275/70/17 or 285/70/17. My question is has anyone done this and what is the before and after effect on mpg . O and i going to a AT not MT as of right now. THANKS any info will be nice....

[Doug_Scott]

Ok everyone im new here and this is my first post. I have a 2009 GMC z71 with stock 265/75/17 tires im wanting to put a 275/70/17 or 285/70/17. My question is has anyone done this and what is the before and after effect on mpg . O and i going to a AT not MT as of right now. THANKS any info will be nice....

 

Around town may drop, highway may increase. Increasing the tire size effectively lowers (numerically) the rear end ratio, so response will be down, making you use more throttle around town, but engine rpm will be lower on the highway. This all assumes you correct the speedo afterwards, otherwise the calculations will not be accurate anyways.