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brianldm
Dodge Dakota
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1/31/2002
19:18:55
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 Subject: Smaller tires = lower gas mileage ?
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I bought lower profile tires recently, went from a 255/55/17 to 265/40/17, and have a question. I am leaving on a long distance trip tomorrow and am wondering if my console will give me the correct MPG rating, and Distance Till Empty (DTE). I know that my speedometer is saying a little faster than it used to and that it will show that Im racking up more miles than I actually am. Anyone know if it will tell me the correct distance till I run out of gas? You know the gauge Im talking about on the overhead consol?
Thanks in advance,
Brian
99 RC RT
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Wayne
Dodge Dakota
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1/31/2002
23:09:33
|  RE: Smaller tires = lower gas mileage ?
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It is incorrect. Part of info it needs to be right is M.P.H. Your shorter tires makes everything wrong.
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Mar
Dodge Dakota
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2/01/2002
10:17:38
| RE: Smaller tires = lower gas mileage ?
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You will gain about 3mph with the bigger tires on the speedo.
you will get more fuel eco because you lowered the gear ratio buy putting bigger tires
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Ben E-Farrer
Dodge Dakota
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2/01/2002
14:52:43
| RE: Smaller tires = lower gas mileage ?
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the DTE should be correct according to your trucks odometer, not the actual reading i think
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R/Truck
Dodge Dakota
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2/01/2002
15:03:52
| RE: Smaller tires = lower gas mileage ?
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When your speedo reads 60 MPH you will actually be going 54.2 MPH. So you can drive 5 or 6 MPH over and still be O.K. with the Law. You may notice a 9.6% drop in MPG on the highway with the smaller tires.
Hope this helps.
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Wayne
Dodge Dakota
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2/01/2002
21:17:32
| RE: Smaller tires = lower gas mileage ?
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Mar, the 265/40s are shorter than the 255/50s. I think R/Truck is right.
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4WD
Dodge Dakota
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2/03/2002
18:45:05
|  RE: Smaller tires = lower gas mileage ?
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Poorer gas mileage. Engines deliver maximum gas mileage when run at ~2/3 throttle. That's why you run in the highest gear possible, to pull the engine hard and squeeze the most power from the gas used.
Since your tires are smaller they act to the engine like a slightly lower gear, thus require LESS throttle for the same freeway speed, thus less mileage. (No, there is not a contradiction there.)
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4WD
Dodge Dakota
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2/03/2002
23:08:14
|  RE: Smaller tires = lower gas mileage ?
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>Since your tires are smaller they act to the engine like a slightly lower gear, thus require LESS throttle for the same freeway speed, thus less mileage.
Rats! I said that wrong. It takes MORE throttle, but the engine is running at a reduced % of max power, thus the gas mileage is poorer. Is that better?
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DeaPee
Dodge Dakota
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2/03/2002
23:33:12
| RE: Smaller tires = lower gas mileage ?
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My view:
smaller tires mean that with every tire rotation, your truck thinks it's gone farther than it did. But, at the same time...it will be easier to turn the tires from a stop. I would say that from a stop, it will use less gas because it will be easier to turn the tires. Probably around 25 miles per hour, the reduction in engine power needed and the over-spinning rear axle will even out and the mpg will be about the same. Anything above 25 or 30, and you'll be getting less miles per gallon than before (like highway driving).
The same thing holds true for over-sizing your tires (but the exact opposite) -- your fuel economy is worse when accelerating from a stop (the engine works harder to spin the big meats), around 25-30 it's equal (they balance eachother out) and anything above 30, you're getting more mpg's.
- Dave
- 01 RC SLT 4x4 3.9 BLACK
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4WD
Dodge Dakota
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2/04/2002
16:31:25
| RE: Smaller tires = lower gas mileage ?
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The reason Dodge has the "shift up now" idiot light (in my 1991s sticks at least) it to encourge you to drive in the highest possible gear. (Wonder if that feature was a sop to the enviros of the day?) Ultimately, to squeeze the best mileage out of a gallon of regardless of other variables require that the engine be working hard.
At the other extreme, the ultimate in poor mileage conditions is to be sitting still and idling, burning up fuel.
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