I recently just did a 2.5 bb on my 99 xj and I was wondering how much of a gas mileage and acceleration difference i would have If i upgraded to 31 inch M/Ts. I currently get anywhere from 12-15 and I’m on the stock 3.55 gears.

Edit: Does anyone have a picture of this setup as well? I’m sure that’s been asked 1000 times but i’ve never seen it with muds.

 

I have a 96 w/4.5" of lift and 31 MT's, stock gears, locked rear axle

I get 11-16 mpg.....mainly due to my normal commute to work being 2.5 miles, with a minimum of 8 stops one way...highway is almost the same as before the lift/tires.

Check your speedo against a gps or measured mile @ 60.

Mine still has the stock gear in it, but is only off by 2 mph @ 60. Seems it was reading pretty high with stock sized tires, which explains why I thought i was getting 22 mpg on the highway.

My 88 w/2" BB & 29" MT's



My 96 w/4.5" & 31" MT's