warthog

I searched but there are so many threads about MPG, i couldnt find the one i was looking for.

I have 98 4.0L stock gearing

So, I am looking to go from 32x11.50's to 31x10.50's to improve gas mileage.

How many MPG do 31x10.50's get on stock gears?

Also would it look stupid with 31" tires on a 4.5" lift?

Thanks

no rdplz

I don't think it'll look bad with 31's on 4.5". As far as mpg, I've got 3" and 31's, stock gears (3.55), and get about 14-15 city and about 19-21 hwy.

warthog

19-21 hwy would be great. I get about 14 tops highway now

mudderx

I don't think it would look too bad but don't get ur hopes up about the mileage. My 98 is on 33's and I get 12 to 15 mpg and my wifes 98 is on 30s and she gets 15 to 17 mpg. Both jeeps have 3.55 gears.So if tire size is worth 5 bucks in gas savings go for it

sluggy

blimey i used to get around 9 mpg [imperial] out of mine round town and about 13 on a run. with 31's on it

prerunner1982

warthog... you may have a high gear set (3.07?).

no rdplz

^^That's a good point. 3.07's will give you lower hwy mpg.

Svrider

yeah im on 31x10.5's and i get around 12-15 mpg highway and city. wish i was hitting that 20 mark like i was on stock tires. My buddy has 30's and hits his 20mpg mark

jdf2010

i have a 4.5 inch lift and 31's and it doesnt look to bad but i think 32's would proble look better.

warthog

I could have sworn i have 3.55's. I will have to get under there to see if its stamped on the diff

Hommersimpson

My motor is in top notch condition.. runs 100% Right...just did a 400 mile round trip to See Gf's Niece.....17.8 Mpg....70 mph all the way...31's 4.5 lift... stock gears...5speed....I would guess... easy 20mpg if id ran 55mph..

Tural

4.5" on HEAVY 31s with LIGHT wheels 15-16 city 19-22 highway, just stay below 55mph.

Caish

The weight of the tire affects performance and MPG.
If you have heavy tires and wheels it will affect MPG as well as acceleration.
Then how much air pressure, on the street you always want air up to maximum pressure.
It decreases the rolling resistance of the tires and will help mpg too.
if your running 3.07's and large tires, quit using OverDrive, this will help keep the
engine in the sweet spot where it gets the best mpg too.

warthog

What rpm would you say the sweet spot is? If that goes off RPM's.

no rdplz

For mine it's about 1900-2100 (about 55-62mph) on the hwy, but again that's with 3.55's, 31's, and 3" of lift.