On my 98 limited 4.0 with 4.5" lift and 31" tires how accurate is the stock overhead mileage reading, it's reading about the same a little lower than when it was stock. 17-18mpg(I drive like a grandma....ok grandmas drive faster than me)

 

17 and 18mpg's are about the average. My 98 gets 16-17 mpg with a 3" lift and running 30x9.50-15.

 

heres the break down of the difference in stock tire size to yours