255/75r17 vs 265/70r17 mileage and speed question.

Relatively new to Tacoma world and first thread I am starting. I currently have 265/70r17 toyo m55's 10 ply on my Tacoma and I was wondering if I would see a large hit in speed and mileage if I went with a 255/75r17 in a 6 ply. Currently averaging 22 mpg with stock gearing in a 2.7 4 cylinder.

 

Welcome to TW!! It sounds like you're considering a tire change that is only slightly different depending on the tire manufacturer. Generally, a 255/75 is only about .3-.5" taller and about .5" narrower than a 265/70. You would need to look at the exact tire's specs on their website. The narrower 255 will actually be slightly better cutting through the wind at highway speeds than the 265. But it would probably be slightly larger in diameter. You may not even notice a MPG difference. However, going from a 10 ply rating (E load) tire to a 6 ply rating (C load) tire usually means a lighter tire. This means less unsprung weight which can definitely affect MPG and suspension performance as well as braking.

You'll need to compare specs on both tires you're considering to know exactly what the differences will be.

 

Thanks! It seems as if the difference is negligible and the 265/70r17 seems to be a lighter tire so I will stick with this size!

 

You'd probably notice an increase in MPG because you're going to a skinnier AND lighter tire.

 

Yep totally agree. I just stepped down from 285/70 to 265/70 and have gained about 2-2.5 MPG back. And I did recalibrate my speedometer with my Hypertech Speedo Calibrator and verified it with GPS so those are real gains. Steering feels lighter, suspension is working better, brakes work better, etc. Still does just fine off-road for me.