I agree with Forest, look at the page below, half the mods are related to aerodynamics, while each one may not have a huge impact every little bit adds up.
65+ Vehicle modifications for better fuel economy - EcoModder.com

These guys are crazy, chop off the mirrors, aerodynamic hub caps, etc. Some of the mods look ridiculous, but THEY WORK!

 

sorry it took so long to get back. I was busy doing this - MBRP Downpipe Install

back on subject. Sorry, let me say I'm speaking about Rolling Resistance...but I called it rotational resistance. same thing IMO. Either way, I'm bored with this argument and you're nitpicking over semantic.


not sure why you refuse to believe that air dams and physically lowering the vehicle, and changing other things like tire size don't work. Guys above posted plenty of proof for both concepts. I highly suggest you give each a try if you ever want to gain some mileage

 

After reading the article from computer cowboy it looks like the dam does provide some improved mpg while protecting the radiator and hiding other things also, plus a debris guard in general and an aesthetic improvement. I'm not the one that commented you on the semantic (resistance/rotational). I still don't agree with your theory on that one either. The wheel weight becomes part of the total truck weight just like your aluminum flywheel theory which holds no water either. Once the clutch is engaged the flywheel has zero to do with ET on the racetrack. I don't nitpick, I just get to the answers.

 

It looks like I was wrong about the air dam but they do have a couple other uses.

 

Simple science experiment

Take some rope and 2 weights. Say a 10 lbs and 15 lbs.

Put each on a 5 ft length of rope. Now spin in a circle and get both weights to spin out centrifugally as high as they'll go. Shoot for waist height for comparison sake

Now which one was harder to get spinning?
Which one was harder to maintain at speed/height?


Imperfect experiment, but it closely simulates what your motor does when you hit the go pedal. This holds true for flywheels or rim/tire. Less weight is easier to keep going. They each have a certain inertia, but that is countered by losses such as air friction and gravity

These losses must be made up for. We'd be in agreement if this were a perfect world and losses didn't occur. Since they do, that takes extra work by the motor; which equates to more fuel burnt

 

You're still not grasping it. When the aluminum flywheel is spinning with the clutch disengaged it will surely attain high rpms quickly but when it is engaged it is a different scenario completely. The engine is now propelling a 4,000 pound vehicle and the couple less pounds on the flywheel has ZERO affect on the acceleration. It's all horsepower propelling the car at this point. If I was suddenly spinning 4,000 pounds at the end of that 5 ft. rope (if I could) that extra 5 pounds would be too minute to measure. The spinning weight of the wheels is the same principle. You wouldn't be able to measure the difference in horsepower it takes to turn a wheel that is 10 pounds heavier at 70 mph. What is 10 pounds compared to a 7,000 pound truck?..........grasping it now?

 

edit: nevermind. you make my head hurt

 

 

Thanks for the input guys... very educational. Update... I'm going to down size to 35's, stick with a MT and go from there. I'm sure gears will be in the near future as well. Thanks again all.

 

M/T tires are a lot of drag on the road. If you are really concerned with MPGs I'd get A/T tires instead.

 

Soooo another update. I'm sticking with the 37's. Let's face it, I didn't buy her for her MPG's. Purchased a Superchips Vivid tuner that should be in any day. Going to get some 4.88's in the very near future. The tuner will help with the towing since we just got a 29' travel trailer, as well as the gears. And the 4.88's should help with the city MPG's as well.

 

Split the difference and go with 36's lol.
I am at the same crosswords. I'm having a six inch lifought on my X soon, and I can't decide between the 315-75-16 or 37's. I want the 37's but I can use my stock rims with the 315's, it will pull better when needed, tires are way cheaper, and of course the mileage will be a little better. In the end I will probably run the 315's in a AT, but keep my eyes open for a 37 tire/wheel combo for playing.

 

Jack, I would have done that as well but this is the way she came. It will be easier for you to carry a spare as well.