By ryan on Tuesday, July 10, 2001 - 11:33 am: Edit

What kind of gas mileage will I be getting if I go for a 2" lift with 245/75-16(mud type) size tires?

By Blue Gill (Bluegill) on Wednesday, July 11, 2001 - 09:18 am: Edit

shouldn't make too big a diff (if you can afford the gas now, you'll still be able to afford it then). I run 245/75 muds, and my last three computations indicated 11.4mpg, 11.4mpg, and a whopping 11.9mpg. The last 11.9mpg was mainly highway, but climbing from 1,500 feet to over 6,000 feet, and spending most of the time at elevations over 6,000 feet. I did, however, manage to break the 300 miles-on-one-tank barrier (300.5 to be exact, running on fumes). I am now determined to break the 12mpg barrier!

By Andy Nix (Andy) on Wednesday, July 11, 2001 - 01:03 pm: Edit

i'm getting between 9.4 and 13.4 with my 245.75's.


andy

By stecz on Tuesday, July 24, 2001 - 08:07 am: Edit

I noticed a big drop in mileage when I went from the 235/70/16s to 245/75/16s. I didn't expect as big of a change in mileage as I got. I used to go about 350 miles on a tank, now, I'm lucky if I break 300.

I guess I'm spoiled a little because my Suburban will go almost 700 highway miles on a tank.

John S.
1997 Disco SE-7

By Bud on Tuesday, July 24, 2001 - 09:03 am: Edit

Are you taking into consideration any increase in the circumference of the tires when you move to a larger tire. This will make the odometer a little bit inaccurate.

Bud

By Blue Gill (Bluegill) on Tuesday, July 24, 2001 - 11:06 am: Edit

yes - larger tire covers more distance per revolution than smaller tire. may not seem much larger, but all that spinning adds up. your speedo was most likely lying to you before, and now it's telling the truth. I can break 300 miles on my 245/75/16's if there's a good tailwind...

By Bud on Wednesday, July 25, 2001 - 02:18 am: Edit

Exactly! That is why I have decided to leave my "winter" tires on. Why not take advantage of the extra "inch" for purposes of fuel and warranty purposes?

Bud

By stecz on Wednesday, July 25, 2001 - 12:39 pm: Edit

The 245/75/16s are only about 5% larger than 235/70/16s, but I got a 15% drop in gas mileage....

By Blue Gill (Bluegill) on Wednesday, July 25, 2001 - 12:49 pm: Edit

you're still not seeing the light...your original "gas mileage" was not 350 miles per tank. You were deceived by your lying speedo/odo. My GPS (which is not infallable, but is pretty damn accurate) tells me that my speedo is now reading correctly with 245/75/16. Therefore, I may have been logging 350 miles per tank with 235/70/16, but I was only travelling 300 or so miles. Basically, you're racking up more miles on the odometer than you're really travelling. That way your Rover is out of warranty sooner...

By stecz on Thursday, July 26, 2001 - 04:08 am: Edit

I understand your point and agree with it, but what I'm saying is that I expected my miles traveled on a tank to drop (because of the bigger rolling diameter of the tires) but not as big of a drop as I got. I was expecting to go down to 325 miles on a tank or so, but I work hard to eak (how do you spell that :-) out 300 miles.

hmmm, I'll have to borrow my friends GPS and test my odometer. Actually, I should do that on all of my cars.

John S.

By Bud on Thursday, July 26, 2001 - 06:36 am: Edit

I think we need to refer this whole issue to our resident Accountant, Les Izmore. Maybe he can decipher fewer being greater and smaller making bigger or not or whatever or.....

Doesn't take much to confuse me.

Bud

By Blue Gill (Bluegill) on Thursday, July 26, 2001 - 07:00 am: Edit

stecz, man.....double-check with a GPS, but I'll bet that you never even were travelling 350 miles on a tank. You just thought you were. When you had the 235's on, you were really only travelling 300 miles over the surface of the earth on one tank of gas; now that you've got the 245's on, you're still going about 300 miles over land. You thought you were doin 350 because that's what the poorly calibrated odometer was telling you. See what I mean? You didn't "drop" mileage from 350 to 300. It probably barely even changed with the "increased rolling resistance" of 245's vs. 235's.

You've got 4 variables here to consider:
1. 235 tire
2. 245 tire
3. odometer calibration with 235
4. odometer calibration with 245

You altered the first two variables, which in turn altered your perceived vs. actual reality (#3 vs. 4).

Most of these people who thing they're getting great gas mileage really aren't. Their odometers rack up more miles per tank than they actually physically travel. Then they slap on 245's and get all discouraged because their odos start telling the truth.

By Steve (Steve2) on Thursday, July 26, 2001 - 09:24 am: Edit

hey bluegil-

i must be lucky as my odo is spot on. if the directions on the map say 22.4 miles - it's dead on with the 235-70's, compared to my jeep which was about 10% fast - the landie does well.

perhaps yours has the wrong speedo gear in the trans? maybe you have the xd speedo gear made for the slightly taller 225-75?

steve