larger tires & gas mileage

[huckleberry668]

for those of you that went 1 size larger, did you notice any mileage decrease?

I'm thinking of going from 265/70x16 to 265/70x17. there are lots of FJ Cruiser 17"s tires/rims sets for sale but not many for the 16"s.

thanks

 

[beirish]

you will notice some decrease. I went from a 265/65/17 to a 265/70/17 and lost about 1.5 mpg or so.

 

[RickyCRX]

I just put some 265/70R17 Michelin LTX M/S's on my 4Runner and my actual calculated mileage number went down slightly if I just take the number of miles driven and divide by number of gallons pumped. However, you also need to then take the MPG number and multiply by 1.031 (or whatever the difference is) to get your real MPG because you actually traveled further than you calculated due to the larger diameter tires.

After doing that, my mileage is right on par with what I was getting before.

Ricky

 

[rook]

If you also add in the fact that you now have a (numerically) lower final drive ratio, as Ricky pointed out, you are going further that the odo indicates, but you are also traveling faster than the speedo indicates. If you also compensate your speed, you may achieve better mpg in certain instances.

 

[Kmvreter]

I upsized from the 265/70/16 Doneflops to 265/75/16 (equal to 265/70/17's) Michelin CT's. I keep very accurate records. As mentioned above, taking into account the 4% difference, I'm breaking even on city mileage and doing better on highway. Overall, I'm ahead of the 3 year previous history. This may be a factor of tire quality, not just size.

 

[jdub24]

Well, I feel better. I guess my loss isn't as bad as I thought it was after all. I think I'm averaging about 14.5mpg according to the vehicle. After lifting mine, and putting the 285s on it, my mileage went WAY down, like 3-4 mpg worse than stock, it was getting 17 or so when my wife drove it every day! Granted, I just can't seem to keep my foot off the fun pedal. Still, I think mileage will always go down when a vehicle is lifted and has bigger tires, that's par for the course....