I lost 3-5 MPG adding 35's.

 

I would check your EBP sensor and tube and make sure they arnt plugged. It's fairly easy to do and won't cost anything. You never know. Mine was plugged right up. But I'm having over boost problems so it never fixed that but the turbo does seem more responsive. Maybe it's just in my head. Lol. Good luck.

Wow. Disregard this post. Not even sure how it ended up here. Sorry.

 

12.8L to 13.8L is a reasonable for the tire, which is 18.3 US mpg to 17mpg, about 7% loss. Heavier and less efficient tread pattern would do it, even if same height.

 

Wondering if he still cares 4 years later.