did you buy from Sac too? i thought there was a dealer in your neck of the woods. i just spent 3.5 hours there today, enjoying the scenery and getting a cracked manifold replaced (gotta love the extended warranty). tried to talk the mrs. into the yellow alpha softop pickup on the lot. i didn't think it was a funny question, but she sure did laugh a lot.

 

That was Brilliant Shorty..I never thought of the tire diameter being a major cause for the inaccuracy, nice catch!...The dealer can to calibrate, or at least it's doable..because how else are they calibrating for the two different tire sizes between the standard H3 packages and the Adventure packages?..275 to 285 is a pretty good difference to throw off calibration...So it must be done at the factory is my guess.

 

the dealerships can change the programming, but only to match the sizes they offer. they can go beyond that, but won't.

the rest, basic physics. it's just hard to get people to understand for some reason. if it's not complicated, for some reason nobody believes it.

and thanks, nice to see someone gets it.

 

I seem to be getting around 16.4 or so over all. it's about a 33/33/33 mix city/hiway/off road. I have had one fill up from just freeway miles, and that was 18+, but on the other end of the spectrum, I filled up, went fourwheeling, and then came back to the same station and filled up again and barely had a double digit number.

I don't complain too much about it.

 

so far i have not engine upgrades and i run bfg all terrain 285-65-18. i get around 14-16 in mostly city. but i'm going to florida at the end of the month so i'll post hwy mileage!

 

Taller tires will throw it off but not enough to bring mpg down that drastically!! Easy way to find out is get a gps and zero out the mileage of both the gps and the trip odo. Take a 20 mile drive or so and see what the mileage difference is. On my Tahoe I went from stock 265 (I think) to 35's and my mileage was off by 2.4 mpg on a tankful.

 

Another way is to measure the height of the tires and multiply by pi on both tires and then look at the difference.

What you really want to be aware of is the actual vehicle speed. I had a stock 91 Toyota pickup and turned it into a Fabtech beast going from 28s to 33s and the end result was I was going 59MPH when the speedo said 50MPH. CHP made me aware of the problem one night in Canyon Country.

 

that's my point exactly. your computer may show a change in mileage, but in actuality the tire size change does very little to true mileage.

 

Shorty is right guys..The taller tires or larger in diameter will throw off you MPG by what the ODO says..Remember, the axles are still turning at the same rate compared to the stock tires calibration, this is as far as what the computer thinks....Hope I said that right.

 

Good thing here is resell. The mileage can be 10-15% less than reality. Of course no one here will buy mine now.