jakbob

and not trying to be a dick... but how do you know your mileage went up? were you running 32s? do you know the difference in rolling distance between stock wheels and 32's (if you didnt adjust your speedo gear) etc...

without data there is only opinion.

nowhres

MPG is not difficult to figure out. No matter the tire size, the equation remains the same.

20 gallon gas tank / distance driven

The airtube and filter gained about 50 miles per tank

Not opinion

Green2000

Ill keep you posted

NewKindOfClown

But if you change your tire size without correcting speedo gear, you need to compensate for distance driven. If you've done that, great. If not, your numbers are off (as well as your odometer).

nowhres

http://www.youtube.com/watch?feature...v=jlSF0dtDRD8#!

NewKindOfClown

nowhres

Okay, I changed my tires over a year ago. When changing tires, I had factory airbox. After changing, I drove my Jeep. 6 months later, I changed my air filter. Equation remains the same

NewKindOfClown

Calm down, I'm just trying to prevent 3 pages of tech questions from the youngins
So whether the numbers are right or wrong doesn't matter; the ratio still shows improvement.

nowhres

That's the same thing I was trying to prevent, lol

And brb, gotta order myself a Sticky Buddy

zwhiz

Sweet pics...whoever took those is a bamf
a couple weeks ago I took my buddy out to bowie state with his wrangler and we accidentally went through that deep spot in the river....he got stuck in it lol

NewKindOfClown

Suggestively sized?

nowhres

I want them rubber fingers.
While I am at it, may also order one of these
http://www.youtube.com/watch?feature...&v=h5qMbk5mL24

NewKindOfClown

I love this guy.


The dub guy...not the guy who posted above me.

jakbob

i cant see the youtube vids at work but...

if you dont correct your speedo gear but increase the size of the tires, the odometer is off. for example (i worked out all this math a while ago, ill give the condensed version)

a 31 inch tire is 109% larger than a stock tire. Therefore, whatever my trip odometer says, i multiply it by 109% to get a better idea of where i am. its all about circumfrence.

which is why my speedo is off (roughly) 5 mph at 55 mph, 6 at 60, but the lower the speed, the lower the difference. its all math. now if my speedo says 120, im actually going about 131-132...

and no, the equation doesnt remain the same. when you change your tire size, you actually insert a variable. and that variable is the difference in distance that one revolution of the tire will net you. since the speedo reads the output shaft of the transfercase, it will always see the same data. so lets say for ****s and giggles, four rotations of the driveshaft equals 1 revolution of the wheel. this wheel is 29 inches long (and we can find the circumference by 3.14(diameter)) so 3.14(29)=91.06 inches. so now we have figured out this:

4 revolutions of the driveshaft = 91.06 inches traveled.

now we increase the tire size to 31 inches.

3.14(31)=97.34

so...

4 revolutions of the driveshaft = 97.34 inches traveled.

so you divide 97.34 by 91.06 to get the percentage increase which is

97.34/91.06=1.068965.

so by increasing the tire size diameter by 2 inches has changed your actual distance per revolution 106.8965%.

this is why your speedo is wrong.

jimmy21669

Yes we get it.

BUT....if my speedo is off with one tank, and off by the same amount the next tank...I can tell if I am saving.


AND


TWSS!