Were my tires throwing off my fuel logs? Help

[random_variable]

Also, your speedometer and odometer are off, but you probably knew that.

[RandomFact314]

OMG**********sigh**** from this change I realize that I should have kept those over sized tires! I got great gas mileage with them ;( and the whole time I thought they were making me get worst mileage >;(

[Christ]

It should only equate to a couple 1/10's anyway. Not enough to cry about.

So where are your air dam, wheel skirts, and belly pan? I bet no one would car jack you if you had all those on there. :P

[RandomFact314]

Originally Posted by Christ

It should only equate to a couple 1/10's anyway. Not enough to cry about.

So where are your air dam, wheel skirts, and belly pan? I bet no one would car jack you if you had all those on there. :P

Nothing to cry about? Lol I was beating my goals and I didn't even know it... AND the LRR tires I bought that I THOUGHT was giving me +1 mpg compared to the old tires actually get -1mpg.....

Don't get me wrong, I'm happy my 90 day went from 30.59 to 33 but erg... that just means I'm not going to be able to get those reading again unless I do something crazy like the airdam, wheel skirts, and belly pan your talking about

[Christ]

Less post - more build thread. MOAR NAO!!!

[cfg83]

RandomFact314 -

Beg, borrow, or rent a GPS to do an odometer correction. I borrowed my wife's :

My Continental Contact-Pro Tires

CarloSW2

[RandomFact314]

Originally Posted by cfg83

RandomFact314 -

Beg, borrow, or rent a GPS to do an odometer correction. I borrowed my wife's :

My Continental Contact-Pro Tires

CarloSW2

I have a gps but I already have gotten rid of those tires

[Christ]

Still a good idea to check and make sure, since the margin of error for some OEM's is up to 5% @ 60 MPH, or 3 MPH correction.

[cfg83]

RandomFact314 -

Originally Posted by RandomFact314

I have a gps but I already have gotten rid of those tires

Hrmmmmm, I apologize for not reading more closely. Even with the tires you have on now, I think you should do an odometer correction test to see if your odo is accurate.

If I were you I would :

1 - Do the GPS odometer correction test on your current setup. Let's say for the point of example that your odometer is incorrect by -1% in your disfavor.

2 - Instead of +10%, make it +9% to be "conservative" in your estimate (because you can't prove it with test data). My wife's GPS shows greater than 2.5%, but I only give myself a 2% credit. I do this to insure that my claimed benefits are well within the range of error.

3 - +9% + -1% = +8% Correction.

4 - Go over your fuel logs and add the data in. I put tons of info my "details" section of my fuel log :

Ignore high/low MPG, only look at AVERAGE MPG (Chevron;91 Octane;#1). 181168 miles on odometer. Tires are larger, so odometer is reading 2% less, hence +2% correction: 248.7 * 1.02 = 253.674

But that's just me. YYMV. (Your "You" May Vary)

CarloSW2