I put on 60,000+/- a year. My question is what is your average MPG with 33" to 35" tires? I would like to run 305/65/18 BFG's but if the MPG is horrible I may have to go with 285/65/18. I currently get 15 on average with stock BFGs on Gryphon 87 performance tune. As long as I don't show a drastic drop in MPG my company will reimburse me for new tires. I am also going home to Michigan in November and would like to hear that I could maintain 15+ MPGs on the way with Bills mileage tune. thanks


Answered my own ? with a search, imagine that! Patience is a virtue........

 

I get 16-17mpg hwy with 315x70x17's on my daily 100 mile round trip commute.

 

I havent seemed to notice that much of a difference, my gas still last's me about the same it did with my stock tires and wheels, which were 255/70/17.
I dont calculate my mpg's though, so i can't say exactly what i'm getting.

 

I get anywhere from 12 to 14.5 depending on how I drive and if it is highway or town driving. My speedo is a little off so I use my gps to get exact mileage per tank.

 

I went from the stock 275/65/18s, to 325.60.18s (33x13) with a different wheel and here is what I am getting.

Best milage recorded-
Stock:21
After: 18

Daily driving-
Stock usually around 14-15
After usually around 13-15


So, mix of town/highway daily driving really hasnt changed too much. Just on the highway babying it, cruise, etc...I suffered a little. Being able to pull 18 if I really want to with a pickup on 33s is still pretty impressive to me though.

 

I was averaging about 14mpg with stock tires with my normal stop and go county road driving. averaged about 17mpg when i made my trip to Pitt. Havent made a long trip on new tires yet but when i went to 325/60r18 i dropped to 12mpg on everyday driving. I dont have tunes yet so when i get those i hope to get back up to 15. maybe too optimistic



2005 Lariat SCAB 5.4L
AF1 3"
Roush O/R
U/D pullies

 

Thanks guys,
I will attempt to post pics after I get new tires.

 

The stop and go city driving is what kills milage with these heavy tires. Highway driving is not too bad.