My 91 4x4 is only getting about 260-270 miles a tank..
Here is something I posted awhile back, about guys who say they get
X mileage based on a tank of gas.
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Jeeeez.........that’s no way to calculate miles per gallon.
I'm NOT trying to make fun of you, though it always throws me, when I hear guys talk about their MPG based on how many miles they went on a tank full of gas.
FYI, try calculating your MPG the "old fashion way."
There is going to be some variance, though I did say it was the "old fashion way." Start by filling up your gas tank, fully.......on level ground........first click off (second click off or whatever) or until you see the gas is it at a certain level in the filler neck (some stations will not let you look some won't).........sometimes you'll have to wait a little for the gas to settle in the tank........or the tank to "burrrp." You don't need to record how many gallons were needed (this time). Though you must record your odometer reading (or set the trip odometer) and remember this fill up procedure.
Any way..........now, drive it...........fill it when needed (don't have to be exact about filling it), log the number of gallons that went in.............drive it some more...............fill it when needed…………………………always logging the amount of gallons that went in............repeat the procedure several times.
After a couple of cycles: of driving, and filling, and logging the number of gallons...........this last time, you're gonna go to the same gas station and follow the same procedure that you used to fill your gas tank the first time that you started your quest for truth. Record this last odometer reading.
So, all done filling her up..............how many gallons was it this time? OK, now add up all of the gallons since you first recorded the odometer. So, how many gallons was the total?
Now, take the beginning odometer reading and minus it from the ending odometer reading………………this number is the total number of miles that you've traveled.
One more calculation left..............now, divide the number of miles by the number of gallons you used..................that number, is your MPG. Use a calculator, if you have trouble.
Now, like I said it's the "old fashion way"............and this method doesn't take into account for an odometer that is not functioning correctly.
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So, what kind of mileage do I get? See my other post on page 2.
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no idea city, as there are no milemarkers to keep track - apparantly the stock tiresize for the 91 was 225/75 and I'm running 235/75, which makes my odo/speedo read about 5-7% low, so I use milemarkers on the hwy to try to keep track of distance travelled.
IMHO.....you went to a wider tire, not a (significantly) taller one......so, the amount of difference would NOT be, as you reported, 5-7% low.
Stock Tire - 225/75R15 >Search Tires Tire 1 - 235/75R15 >Search Tires
Section Width: 8.85 in 225 mm
Section Width: 9.25 in 235 mm
Rim Diameter: 15 in 381 mm
Rim Diameter: 15 in 381 mm
Rim Width Range: 6 - 8 in
Rim Width Range: 6 - 8.5 in
Overall Diameter: 28.28 in 718.31 mm
Overall Diameter: 28.87 in 733.29 mm
Sidewall Height: 6.64 in 168.65 mm
Sidewall Height: 6.93 in 176.02 mm
Radius: 14.14 in 359.15 mm
Radius: 14.43 in 366.52 mm
Circumference: 88.84 in 2256.5 mm
Circumference: 90.69 in 2303.5 mm
Revs per Mile: 735.5
Revs per Mile: 720.4
Actual Speed: 60 mph 100 km/h
Speedometer1: 58.7 mph 97.9 km/h
Speedometer Difference: - Speedometer Difference: 2.096% too slow
Diameter Difference: - Diameter Difference: 2.05%
You can try your own calculations here:
http://www.1010tires.com/TireSizeCalculator.asp?action=submit
Aloha, Mark