jonsommer said:Here something to think about. Will the transmission shift at a late time keeping the Motor rpm higher for a longer time lowering the MPGs.
The more revolutions your motor makes the more fuel it requires, actually it is that simple.03dynasty said:Another thing to think about is a bigger tire is heavier, you can't slap a 38" tire on that thing and expect better mpg. Also rpm's are not directly related to mpg. Of course you will get bad mpg if you run at 5k rpm's all the time but you'll also get bad mpg when the motor is being lugged. It will be wasting fuel. The car was built from the factory to take a certain sized tire and geared accordingly. However I don't think you'll see much of a difference, the difference in diameter is ~3%. Things are not so simple since your mpg is ultimately determined by the amount of fuel it burns and you don't know which size your motor/trans prefers. On the plus side your odometer will read 3% fewer miles (3k miles per 100k)
jonsommer said:This is interesting there seems to be two trains of thought.
If RPMs Lower MPGs how do you explain why my 1985 S10 pickup got better MPGs running at 65MPH then 55MPH. The average increase was about 3MPGs.
I did alot of long distance runs for the company I worked for. It was a 2.8 V6
4 speed with eagle GT tires. The 4 speed was rare for a S10. Average MPGs was about 23.
Question : What air pressure should I be running in the 235/75-15?
The first reason to believe of dismiss an argument is because of personal experience. if this guy said he got better mileage at 65 as opposed to 55 and he is talking from experience then you cant say he wont.Jetmeck said:Unless you are running an aftermarket cam of some kind that changed the factory power curve
you won't get better mileage at 65 than 55. Run the tire pressure as stated on the sticker inside the door jamb of your vehicle unless these are not the factory size tire.
Some of you can be hard headed at times, but in it's simplest terms. Do any of you really think a vehicle
that has a higher numerical gear installed or a shorter (smaller diameter) tire put on it will get better mileage ? Each of these cases will increase the vehicles RPM at any given point as compared to factory.