tire size versus gas mileage

[wnl25]

How much gas mileage do you gain going from a 30x9.5x15 tire to 235/75R15 on a 95 jeep grand cherokee with 4.0 inline 6 motor?

 

[superj]

what do you get right now? and you are in the wrangler section, not the cherokee section.

my old zj got about 20 on the highway with stock tires

 

[jps4jeep]

probably will loose milage depending on where you drive. if you drive a lot on the highway, a 30" tire compared to a 29" tire does not offer enough rolling resistance to lower milage, but the slight increase in tire diameter, will slightly lower RPM's and maintain overdrive, hence slightly less fuel consumption.

 

[Bounty__Hunter]

How much gas mileage do you gain going from a 30x9.5x15 tire to 235/75R15 on a 95 jeep grand cherokee with 4.0 inline 6 motor?

.31 mpg

Really there's way too many variables for an answer to this type of question. Mileage could go up if the drivetrain was geared to tall and the engine was struggling at highway speeds. Mileage would go down if the drivetrain was geared too low and the rpm's go up at cruising speeds.