Bumping up one tire size/expected loss in mpg?

[IMPALADAKID]

Sorry to bring this back from the dead, but I can get the tires I want cheaper by going to a bigger size. The difference is 1" bigger. 265/65/18 vs 265/70/18. I will get the truck tuned for the difference. I plan on a leveling kit at the same time up front. Any reason I should not do it, and just stick with the stock size? The bigger size is $9 cheaper per tire.

[Donstar]

Sorry to bring this back from the dead, but I can get the tires I want cheaper by going to a bigger size. The difference is 1" bigger. 265/65/18 vs 265/70/18. I will get the truck tuned for the difference. I plan on a leveling kit at the same time up front. Any reason I should not do it, and just stick with the stock size? The bigger size is $9 cheaper per tire.

I recently asked a similar question with no response. I believe that your truck will look better with the bigger tires and that a re-tune is not necessary. I've been wondering about going from a 255/70/17 to a 255/75/17 which is also about an inch difference. My main concern is whether it would give a tall skinny look to the tire. On the other hand, this may be a refreshing change from the typical tall, wide tires!