Mpg, tire size and ratio

[Ranger4x4newb]

I've got a 98 4.0 with 33's all the way around. It's an auto 5 speed 5r5te with stock 3.73 and a body lift. Im getting close to 14mps hwyand about 11 city. Would rgearing to a 4.10 or 4.56 help? I do a good amount of street driving but some highway too. I'm not sure if there's a motor problem or tire size issue going on. It has new plugs wires and coil plus a k and n panel filter on it so i know there shouldn't be anything wrong there right?

 

[gw33gp]

It is difficult to predict gas mileage with changes in tire size and gear ratios. Going to larger tires can pretty much assure you that you will get worse gas mileage.

I have been running 31x10.5" Michelin LTX M/S tires on the street for a long time with 4.10 gears. I got around 16 mpg around town and 18-19 on Interstates. When I put my 32x11.5" MT tires on for off-road the gas mileage would drop to 15 around town and average about 17-17.5 on the Interstate. I then went to 33x10.5" MT tires for off-road and installed 4.56 gears. My around town gas mileage is now about 15 mpg and 18 Interstate with the 33" tires on. With the 31" tires and 4.56 gears I get around 15 mpg and have not taken a long trip to know what I get on the Interstates.