With my 2.7 with a stock roof rack I get about 21mpg .Now that the weather is warmer my last tank was about 23 mpg .Thats pretty well 80% highway the rest city .

 

I calculate the difference in tire size between the stock tires and my current tires, which is about 12%. I add 12% to the number of miles I've gotten for that tank of gas. Then divide that number by the number of gallons I put in the tank.

So basically...
- I pull into the gas station with the trip reading 286 miles
- add 12% to that to account for the larger tires
- total miles driven are approx 320
- fill up the tank with approx 12.9 gallons
- estimated gas mileage = 24.8 mpg

 

Either my math is off, your truck came with tiny tires, or your vastly over-estimating your % difference in tire heights. Assuming your new tires (32's) are 12% larger than they were before then before you had a tire height of 28.57. ...Anyone know

 

Easy way to validate is to use a GPS, it will give you a good idea of miles travelled and on the highway you will get a good idea of your speedo error.

These devices are pretty accurate, and can save you a fortune if like you have bigger tires and an under reading speedo and traffic fines

12% sounds like a lot, check the tire manufacturer chart for your old and new tires to get the true diameter of the tire. DOnt assume if they say 32" it is a 100% 32". ANother good one that is listed which will work better is the revs per mile indicator.

 

wow, 25mpg would be cool. after all the mods i've done i'd be happy with 20mpg. right now i get about 275 miles per tank.

 

Yup... the stock Firestone Wilderness ATs were 225/75-15, which according to the firestone website are 28.3" in diameter.

 

Here's a tire size calculator. The diameters for the different sizes don't always match the numbers for the brands at tire rack but are close.

http://www.miata.net/garage/tirecalc.html

 

Dang those are tiny tires. I didn't know they used tires that small anymore... much less 15 inch rims on the 96+. Either way, that begs another question. I wonder if they bothered to calibrate the speedo/odometer for each different tire size.

 

I'm right at 270-275 with a Yakima rack w/fairing and dual Steel head bike mounts, and a 2" lift. I have't recalculated since I went from 265/70/16(30.61") tires to 265/75/16(31.65") tires.

 

These are the 225's!!!


These are a real set of tires!


Sorry to put you on stage jackson, I just thought pics are worth a thousand words.
BTW, you still liking your OME HD setup? Any sagging?

 

Checked the bridgestone/firestone site

the 225/75/15 wilderness gives 736 revolutions per mile
the 32/11.5/15 duler gives 659 revs per mile

so it's 11.7% difference

consider yourself very lucky to get that mileage with those big wheels (truck looks great, what a difference)

you still might want to check with GPS, or smile and be happy very happy and show a big middle finger to OPEC

 

Regarding speed/gas mileage; about a month ago I had the fine testing ground of I80 across Iowa and Nebraska to see how speed affected me. Using the cruise, I'd do an entire tank at one speed, then another. I noticed the an amazing difference between 75mph and 70mph, I went from 18.5mpg at 75 to close to 22mpg at 70-I couldn't bear to run a whole tank at 65, but I bet I could have approached 25mpg. I have pretty much stock tires, size-wise (I think).
Just my .02

 

LMAO!!! Yes, they are. Well, actually those are 235s (they replaced my stock 225s)... so the 225s are actually smaller than those. Though I don't think you could tell in a pic. And thanks for bringing up such an old picture. I had almost forgotten how far my rig had come in the last few years.

On a related note... I had also almost gotten over that glow-in-the-dark front door on the house. I guess it's back to therapy.







No problem... you're exactly right about the pics = 1000s of words. As for the OME... nope, no sagging at this point. I'm hoping to get a winch on it this summer - that will be the real test.

 

Dang you did get some lift! But aren't those 16 inch wheels? I didn't think 15's would even clear the brake rotors/calipers.

 

Nope, stock 15" rims in both pics (both the before and after)... that's why the calipers aren't an issue.

 

I`m running 265/70/16 on mine and I think that s why my mikeage is so ˟˟˟˟ .

 

On mine I run 265/75/16's and I get about 300 miles per 16.5 - 17 gallons, on average if i'm doing very good.