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DirtyKK · **Posted:** Wed Feb 03, 2010 9:38 am

Elt31987 wrote:

DirtyKK wrote:

Elt31987 wrote:

The average Revs Per Mile for a 245/75/16 is about 684 and for the original 225/75/16 is 708. Would the 245/75 have worse or better MPG based on Revs Per Mile?

your mileage would show worse. since your tires are larger you will have driven more miles then your trip would say you had. when you divide with the # of gallons of gas you would be dividing by a lower number then what is accurate. making it seem as if your mileage is actually worse then it is.

HMM ill have to try and do the math, my friend said if i divide 708 by 684, then multiply that by the miles my Tripometer says that will give me a more accurate mileage. Any mathmagicians want to comment?

708/684 would give you the % the tire is off. 708/684 is 1.035~ meaning your tire diameter changed for 3.5% ish so that might be about right.

haulin5 · **Joined:** Tue Sep 29, 2009 2:53 pm **Posts:** 116

I'm working on a spreadsheet right now in Excel for all things tire-related.

The circumference, in inches, of a 245/75/16 is 95.7". There are 63,360 inches in a mile.
The number of revs per mile is therefore 661.9, or 662 for rounding's sake.

Using the same calculation, the # of revs for a 225/75/16 is 688.6, or 689.

Your ratio would therefore be 689/662, or 1.04078. That translates to your mileage being 4% better than what your odo is telling you.

So your friend's math was pretty darn good!

Elt31987 · **Posted:** Wed Feb 03, 2010 1:55 pm

Using http://www.miata.net/garage/tirecalc.html you can calculate your Revs Per Mile for the new tire and the old then Divide the old Tire by the new Tire then multiply that number by the Amount of Miles your Jeeps said you drove then divide that by the amount of Gallons the pump says you put in to get your MPG. This should work with any tire size as that site lets you select different sizes.

nightdrv · **Posted:** Wed Feb 03, 2010 9:53 pm

tools113 wrote:

Average 20 MPG
Highway - 70 -75 mph - 23 mpg

Something strange about that Jeep... I get 17.5 avg, but I do have an aero box on top, and different size tires. But 20 avg? That's nuts. You must drive reeeeeeeeeeeeeally carefully.

wecwbe · **Posted:** Wed Feb 03, 2010 11:02 pm

Diggerfreek wrote:

Ah, if your motor act like mine, you will notice it free up around 5K

What should I expect will happen to the mileage? Up or down? Does it respond any differently (power or torque) after 5K?

wecwbe · **Posted:** Wed Feb 03, 2010 11:16 pm

onlyina wrote:

It seems like the 2010 changes with the fuel saving devices really work!

onlyina, if you are talking about my MPG numbers, I have to admit, I have been a bit hypnotized by the EVIC read out of average MPG and it has made me drive more carefully trying to maximize the number sometimes. As somebody once said, "I don't mind moderation as long as I can have lots of it." I'm sure my natural moderate lead-footedness will return after the novelty wears off. :lol:

When you've driven a TJ for 11 years, an EVIC digital readout is almost a religious experience. :dizzy:

zarinKK · **Posted:** Wed Feb 03, 2010 11:33 pm

Elt31987 wrote:

HMM ill have to try and do the math, my friend said if i divide 708 by 684, then multiply that by the miles my Tripometer says that will give me a more accurate mileage. Any mathmagicians want to comment?

A 245/75-16 is about 4% larger than stock 225/75-16 so just multiply your miles on your odometer by 1.04 then divide by gallons.

Elt31987 · **Posted:** Thu Feb 04, 2010 8:07 am

zarinKK wrote:

Elt31987 wrote:

HMM ill have to try and do the math, my friend said if i divide 708 by 684, then multiply that by the miles my Tripometer says that will give me a more accurate mileage. Any mathmagicians want to comment?

A 245/75-16 is about 4% larger than stock 225/75-16 so just multiply your miles on your odometer by 1.04 then divide by gallons.

Ya figured it out a few posts back, Thanks tho :pepper:

zarinKK · **Posted:** Thu Feb 04, 2010 8:11 pm

Elt31987 wrote:

Ya figured it out a few posts back, Thanks tho :pepper:

Yeah, I only read the first page of this thread then hit reply. DOH! :banghead:

My bad.

Elt31987 · **Posted:** Thu Feb 04, 2010 8:55 pm

zarinKK wrote:

Elt31987 wrote:

Ya figured it out a few posts back, Thanks tho :pepper:

Yeah, I only read the first page of this thread then hit reply. DOH! :banghead:

My bad.

Haha its all good

RPM007 · **Posted:** Fri Feb 05, 2010 3:24 pm

Holy Geez. My EVIC claims I am only getting an average 13.3 mpg. I drive the KK pretty hard, but it can't be that bad. I am going to have to get mathematical and figure out what kind of gas mileage I am really getting.

Elt31987 · **Posted:** Fri Feb 05, 2010 3:31 pm

If your hard on the skinny pedal it will get bad MPGs :jester:

jeeplikens · **Posted:** Fri Feb 05, 2010 3:34 pm

Liberty is almost 1 year old. 35k miles. Most highway.

Best: 26.7 hwy at 1800 rpm between Detroit and Chicago. was 25.9 going, 26.7 return
Worst hwy: 22.3 at 2500 rpm (mostly 75-80mph) Detroit to Chicago (summer time)
City: Best 17mpg
Worst 11mpg

Worst over all was when I was pulling a fully loaded 8x12 uhaul for 2 days.

Now that I got a tune up (30k service) I seem to be getting about 300miles out of a tank city. I think that's not as good as before, also got new tires. Letting car adjust but think the tune up has my mpg screwed up :dizzy:

I do have a K&N airfilter in and have since it had 2k miles on it and I run 87octane fuel.

I'm overall happy with my MPG and blows my 04 away in that area.

Elt31987 · **Posted:** Fri Feb 05, 2010 3:37 pm

jeeplikens wrote:

Liberty is almost 1 year old. 35k miles. Most highway.

Best: 26.7 hwy at 1800 rpm between Detroit and Chicago. was 25.9 going, 26.7 return
Worst hwy: 22.3 at 2500 rpm (mostly 75-80mph) Detroit to Chicago (summer time)
City: Best 17mpg
Worst 11mpg

Worst over all was when I was pulling a fully loaded 8x12 uhaul for 2 days.

Now that I got a tune up (30k service) I seem to be getting about 300miles out of a tank city. I think that's not as good as before, also got new tires. Letting car adjust but think the tune up has my mpg screwed up :dizzy:

I do have a K&N airfilter in and have since it had 2k miles on it and I run 87octane fuel.

I'm overall happy with my MPG and blows my 04 away in that area.

what car??? :twisted:

zarinKK · **Posted:** Fri Feb 05, 2010 3:42 pm

The MPG drop is most likely from your tires being heavier than the stockers.

And your MPG numbers are by far better than I've ever gotten

Don't think I've ever hit 300 miles on a tank even when using about 18 gallons of fuel. Maybe if I pushed it and used all the fuel I could get 300.

KKeith · **Joined:** Thu Oct 09, 2008 3:06 am **Posts:** 58

Our CRDs are up around 32MPG. :JEEPIN:

Elt31987 · **Posted:** Sat Feb 06, 2010 10:53 am

KKeith wrote:

Our CRDs are up around 32MPG. :JEEPIN:

Diggerfreek · **Posted:** Sat Feb 06, 2010 1:57 pm

Elt31987 wrote:

KKeith wrote:

Our CRDs are up around 32MPG. :JEEPIN:

X2

Shadow's_Jeep · **Posted:** Thu Feb 11, 2010 11:04 pm

In town we get between 14.5 to 15.8 depending on how heavy my foot is.
On the highway we get between 21.6 to 23.8 depending on speed. 60mph to 75 mph

loosvelt · **Posted:** Sun Feb 14, 2010 1:26 am

For you guys with lifts and bigger tires, do you think you lost more mpgs from the larger size or the great weight? In theory wouldn't you get better hwy mpgs with larger tires and the lowers gears (assuming you didn't regear)?

MPG

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