I said in a statement earlier that pleasedidgevan2 was the only one who came close to the real proble, As I look closer, Triedaq and same mountainbike are also right.
And Stoveguyy, you aren’t going as many miles as you thinkk you are. And if you use a MPG indicator you aren’t going as far as IT thinks you are. That might not make ALL the difference, but certainly some of it.
You say the tires are 3.7% smaller so when you show 1000 miles on the odometer, you have actually gone only 960 miles… That is if your figures are correct.
1000 miles divided by 33.3 gal = 30 MPG. 960 miles divided by 33.3 gal = 28.8 MPG. I believe that is a 4% increase (using your figures)
Intuitively I would agree with EE & TSM on this. The mileage computations can theoretically be quite accurate but they are dependent on several inputs and the change in one input may grossly alter the equation. The wind drag may be at some peculiar threshold at 75 miles per hour and dropping just 4 mph both decreases the drag significantly while it overstates the mileage. Also, the small difference in tire diameter might allow the transmission to shift into OD much sooner and remain in OD to a greater extent. My experience with replacing 215R15s with 235R15s proved costly in performance and mileage on an S-10. It was unable to hold 65 mph on level roads in OD. I rarely shifted to OD with the larger tires installed.
Yeah, RED, altho larger tires work like an overdrive, sometimes they just don’t help the MPG, because, as you say, the vehicle just isn’t able to handle the extra power needed to pull the larger tires. I bought a new Dodge 1500 a few years ago with a 318 engine and an overdrive transmission and 16 inch tires. I would have been as well off with a 3 speed auto.
By whatever name, Whitey. The power band of an engine can be mismatched to the load with a poor final drive/wheel diameter combination. When driving at 70 mph and shifting to overdrive results in the speed declining with the throttle wide open the problem is quite apparent. But if the over gearing is short of being so obvious it will show up in performance and fuel mileage. And the horsepower/torque picture is just too muddy. Like Rawshack images there is too much room for personal interpretation.
You will never lose an argument until you admit when you are wrong. I wish I had some of the stupid things you have said over the years. Like “” I don’t think the ability to turn larger tires is a matter of “power” (i.e. horsepower). I think it’s a matter of torque"" How stupid is that? Since when did Torque cease being Power? .
“. . .stock tires are 26.6” I put on a 2nd set of used tires that are 25.6" or 3.7% smaller. . ."
Let’s take this from the beginning. Your orginal tires are 60 series and your replacemnt tires are 50 series. Could we have the tire size so we can recheck the diameter of the wheel with the tire? I’m wondering if the replacement tires are more than 3.7% smaller in diameter.
Elly, if you don’t understand the difference between horsepower and torque, I’m not going to be the one to explain it to you. With your level of comprehension and stubbornness, that could go on forever. Besides, I think your time would be better spent using Google to figure it out for yourself.
The only “stupid” things you keep reciting and attributing to me are either misquoted or taken out of context. Those who know me know better than to fall for that kind of foolishness.
I’m sure I could cite things you didn’t say, claim you said them, and make you look stupid too, but I’ll let you do that for yourself.
I never mentioned horsepower, you did. Power and torque are closely related, if not twins
.I’m sure you could cite things I didn’t say, claim I said them, and make Me look stupid too, and you usually do.
I Googled the difference between horsepower and Torque (Remember I said power in my post) and found a lot but I wanted you to see this part. "“So, if you want a quick answer to the difference between horsepower and torque, just keep in mind that horsepower involves the amount of work done in a given time, while torque is simply a measurement of force and is thus a component of horsepower.”“
Please note the last part, “” thus a component of horsepower.”"
I don’t believe that the word “Power” was wrong in my post. @whitey, you would find fault if I said it snowed here in the Midwest last night. (about 10 inches) If I asked you to hold up my car while I changed a tire, would you be short on power or torque??
Read Pleasedodgevan’s post. I agree with him.
Because your smaller tires have spun more times over each mile thanyour OEM tires that the computer was calibrated for, the computer THINKS you’ve gone farther than you have. At the same time, it’s reading the fuel used, and is determining thta you’ve gone father on a gallon than you actually have.
Other things figure into the equasion, but this is the answer to most of the difference.
Yup, and that’s what I said, only using different words. We all agree.
The challenge is how to explain it to the OP, along with how that fact causes his gas mileage calculation to differ from his true gas mileage.