Trying to make a MPG chart for tires/gearing. Please post here...

Ok, so heres the deal. Alot of threads I read have people asking about what MPG they may expect from different tire/gear combinations. I know other mods and vehicle condition and what type of tires you run has an impact on this as well, but leaving that out, I want to start a thread where anyone and everyone posts what tire/gear combination they run and what avg mpg they are getting. I also want to keep track of if its an auto or 5 speed and what engine is being run. Then from time to time I will make/update a spreadsheet with the averages for each tire/gear combination that gets posted here, keep one chart for all Jeeps (with the same engine), one for all automatics, and one for all 5 speeds. Then when I get enough going, I will post the sheet I get made, and as more people post responces I will update and repost as necesary or requested. If possible, leave the tire size, gear ratio, the year, transmission, and engine you are running along with your avg fuel economy and I will see what I can do to get a chart with all the info in it so this question can be answered once and for all in a single location, and not have it be based on theoretical values.

Along the same lines, feel free to also leave your opinion of the tire/gear combination. I will keep a running list of everyone who posts and organize either by tire size or gear ratio, so anyone who wants to know how a certain combination will be can pull this up as well and see what people have said. Just trying to clear up a couple of the major questions that always seems to overload this thread (and I will admit, I am guilty of asking the same questions before too).

If people want this i would be glad to do it, just post here and get others to post here, and keep this thread active so people will see it and go with it. The more I get the better it will be. And for accuracy purposes, it would be great if all measurements could be made based on testing it, dont just guess... I will try and get a 2nd post up soon with what to multiply the miles recorded by the odo by in order to get actual miles traveled (for those of us who havent corrected the speedo/odo) if anyone wants.

Scott

about 14-16mpg on 35s with 4.88s

4.10's with 31" tires. Manual 5 speed. 2.5 litre engine. Around 13 MPG.

14 city/19 highway

31 inch tires, 3.55 gearing, auto

33" tires 4.56 gears ~ 14-16mpg

89 XJ 4.0L 3.55 auto 235/75/15, 19 to 24 MPG (with using acetone)

This is pointless unless you're asking about lift, roof rack, driving style, driving conditions, etc. Anyway my 89MJ 4.0l, auto, 32s, 4.10 gears, lifted 5.5", gets 16-18.

1992 4.0 LT235/75/15, auto roof rack 4 lights 2 can and tyre. 2" lift,
14-19mpg

1990 XJ, 4.0, AX-15, 31" tires and 3.07s: ~16 MPG city, ~21 highway.

The gearing sucks; I never see fifth gear.

As I stated earlier, I do understand that those all greatly affect the mileage, When lifting, drag is increased, but in some ways lifted is lifted, I know people running lifted jeeps with 31s and others running jeeps lifted far more than the previous people, while running the same tires, and getting compareable gas mileage (otherwise they have the same setup). So within reasonable limits, once lifted, that seems to increase the drag to a common area. And this is also assuming anyone running, say, 33s, will have a lift. I am just trying to HOPEFULLY get a decent number of responces, which will give a base idea for what there is. I am sure some people who will respond will have roof racks, and some wont.. I will avg everything from diffrent tire size and gear ratio combos together to get an average. As far as driving style, thats also a given, but again... trying to get a running average.

lawsoncl said:

This is pointless unless you're asking about lift, roof rack, driving style, driving conditions, etc. Anyway my 89MJ 4.0l, auto, 32s, 4.10 gears, lifted 5.5", gets 16-18.

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pointless, but you'll jump in anyway :roll:

From the data so far we can deduce:

32's get better mileage than 31's, but 35's are only 1mpg worse than 31's
The 2.5 4 banger gets worse mileage than the 4.0
89's get better mileage than all other years
acetone really works :roflmao:
5 1/2' lifts get better mileage than 3 1/2" lifts

garbage in, garbage out

What is the acetone for?

Acetone is a fuel additive that helps clean out the engine, which is the only reason why it is said to improve fuel economy. Do a search on it, theres at least one thread on it out there, and a number of sites if you google it

OK. thanks.

DIABLOBLANCO8658 said:

What is the acetone for?

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they recomend using 3 ozs / 10 gallons, i use about 4 ozs / tank (20 gallons), seems to work, dont expect it to fix sensor or mechanical problems , and stay away from stations that have ethonol, unless u are going for a emmisions test next month.

this is my 10 cents.!!!1

If your TPS is bad, will it decrease your MPG?

SLAYER said:

If your TPS is bad, will it decrease your MPG?

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yes. at least most of the time, if it runs right.

4.56's 32" mud terrains, 4.7l stroker, 16 city, 19 highway (~65mph)

lucky bastard with a stroker... thats all I have to say.. at least now I know what to expect for fuel economy when I get mine, hopefully in a year

35's, 4.56's, 12-13.5mpg highway driving between 65-80mph. Its a brick, its gonna get crappy mileage, but I don't think the chart would be pointless. At least just as pointless as those gear calculators people always recommend that never take into consideration weight, wind drag, true tire size, etc.