Gas mileage

[Jeepcowboy1977]

Hey guys I got my 2005 Jeep liberty last year in late November drove it twice and had to rebuild the whole front end and add new lift kit but last owner changed the tires from 235 65 17 to 235 70 16 basically the same size tires from stock they had a 2” lift but was sagging and had a bad lower ball joint that failed. Now it’s done other then the rear end part of the lift so I’ve been tracking my mileage with a mileage app on my iPhone so when my liberty is new average MPG says 17 mpg but after driving no highways but country roads and city roads I’m getting 326 miles on a full tank then I’ve filled up again and again and still getting over 300 miles on a full tank at 18.6 to 18.8 MPG it’s making me happy so for a 19 year old jeep with this type of mileage should I go ahead and run a bigger tire right now I’m at 29” tires but thinking about 31” would it be worth it driving 100 miles daily or stay with the 29” and only have the bigger tires for off roading

 

[KJowner]

Good job you have cheap fuel in America, mine averages 25MPG in normal use and 28MPG sitting at 70 ish. Diesel is $7.4 a gallon here.
Not sure what affect the tyres will have, they aren't massively different.

 

[slowcrawlerZJ]

Nice little Libby you got there. My 2 cents is if your daily driving it 100 miles I’d just stick with the 29’s. Your transmission and gas mileage will thank you. I run just over 31 inch tires but my Libby is just a toy for camping and off-road. I drove it for about a week just to see what kind of mileage I was getting and it floated between 15 and 16 mpg.

 

[Scoot]

Hey guys I got my 2005 Jeep liberty last year in late November drove it twice and had to rebuild the whole front end and add new lift kit but last owner changed the tires from 235 65 17 to 235 70 16 basically the same size tires from stock they had a 2” lift but was sagging and had a bad lower ball joint that failed. Now it’s done other then the rear end part of the lift so I’ve been tracking my mileage with a mileage app on my iPhone so when my liberty is new average MPG says 17 mpg but after driving no highways but country roads and city roads I’m getting 326 miles on a full tank then I’ve filled up again and again and still getting over 300 miles on a full tank at 18.6 to 18.8 MPG it’s making me happy so for a 19 year old jeep with this type of mileage should I go ahead and run a bigger tire right now I’m at 29” tires but thinking about 31” would it be worth it driving 100 miles daily or stay with the 29” and only have the bigger tires for off roading

On my liberty I have a 2.5 inch lift and 32 inch tires and I get about 12-13 mpg with a mix of highway and city driving. Although getting the bigger tired to fit in the front did take some modifications. you would have to cut the front bumper and bend some pinch welds in the fender. But I think it's worth it especially if you go off-roading. Plus it looks pretty cool to have big tires.

 

[WheelNut]

I have 245/75R16 (30.5") on my KJ and I think I'd go for 245/70R16 (29.5") if I were to replace them. I had 245/70R16s on for 2022. The difference offroad was pretty marginal in my mild offroad driving situations. The 29.5" tire fits the KJ better and suits the gearing better for city driving. The 29.5" looks good on the KJ too- fills the wheel wells nicely.
Note that the 245/75R16 will fit with dang near zero rubbing (stock wheels 16x7 ET41) with no mods and standard bumpstops.
255/70R16 is also a good choice if you want to go over 30". The extra width will look really good and the tire has more volume inside it than a 245/70, so you can run a bit lower pressures offroad. 255 width won't rub your suspension components with your wide offset wheels. Not sure how much rub you'll get on the fender lines and pinch weld.

You're fuel economy numbers are looking pretty good. Engine must be pretty running well.

 

[Scoot]

I have 245/75R16 (30.5") on my KJ and I think I'd go for 245/70R16 (29.5") if I were to replace them. I had 245/70R16s on for 2022. The difference offroad was pretty marginal in my mild offroad driving situations. The 29.5" tire fits the KJ better and suits the gearing better for city driving. The 29.5" looks good on the KJ too- fills the wheel wells nicely.
Note that the 245/75R16 will fit with dang near zero rubbing (stock wheels 16x7 ET41) with no mods and standard bumpstops.
255/70R16 is also a good choice if you want to go over 30". The extra width will look really good and the tire has more volume inside it than a 245/70, so you can run a bit lower pressures offroad. 255 width won't rub your suspension components with your wide offset wheels. Not sure how much rub you'll get on the fender lines and pinch weld.

I agree 245/70 is definitely the best size for the liberty

 

[Jeepcowboy1977]

Nice little Libby you got there. My 2 cents is if your daily driving it 100 miles I’d just stick with the 29’s. Your transmission and gas mileage will thank you. I run just over 31 inch tires but my Libby is just a toy for camping and off-road. I drove it for about a week just to see what kind of mileage I was getting and it floated between 15 and 16 mpg.

I was thinking the same say with the stock but maybe a more off road tires

 

[ikuo78]

If you change the tires from 29 inches to 31 inches,
When cruising at 100 km/h, the motor speed will drop by about 100 rpm.
If there are fewer slopes,
This will effectively improve fuel efficiency.

It's a good idea to use GPS to accurately measure the impact.

Odometers only measure the number of rotations of the tires, so they cannot give you an accurate distance.

 

[lfhoward]

If you spend the money to regear your differentials, you can compensate for tire size differences and the engine will run in the stock rpm range:

29’s - 3.73
30.5/31’s - 4.10
32’s - 4.56*

*KK 08-12 model years only. KJ can only go up to 4.10 gears.