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Discussion Starter #1
I was just wondering if any one had an idea of how to account for true distance traveled for MPG's when dealing with oversize tires. i have 37" tires and according to estimates im getting 12 MPG's but i know this is inaccurate considering i am traveling farther than with the stock tires which i believe were 31" tires. any help would be greatly appreciated and would be beneficial to more than just me i am sure!!!
 

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Correct your speedo then measure it by hand. Or take a trip a few hours long over a fixed distance then measure your burnt fuel.

Is it the 250 or ex?
 

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not sure since yours is an ex, but with my cc, i determined that my tires are about 15% off, so fuel econo is about 15% better than the console.
 

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I have oversized tires and what has always worked best (without re-calibrating) is to compare your odometer to the mile markers along the road and then once you figure out how far you are off you can calculate everything to get the percentage. I have 35s and it is about 10% off. I know it wont be exact but it will get you a lot better estimation to your fuel milage.
 

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Discussion Starter #6
see i was on a different forum, i think the tundra forum, and they said some weird equation and i can remember what it was but it ended up being like tire size divided by old tire size times miles traveled equals your true miles traveled with oversize tires. i was hoping somebody could add some validity to that claim.
 

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Just multiply the miles registered on your odometer times the ratio of the big tire OD over the little tire OD to get a rough idea. (Trip miles * (Big OD/Little OD))

If you want to get more particular, you can look up the specific rolling radius/diameter of the stock tires and your big tires, and use those numbers in the ratio.

If you want to get even more particular, you could nab yourself a GPS and keep track of miles traveled with it.

And if you still want to get even more particular, make sure you fill up at the same pump at the same station facing the same direction parked in the exact same place everytime, and fill up to the top of the neck each time.

I usually like to compare my most accurate hand calculated miles to my GPS miles, just as a back check.

I just hand calculated my mileage over the last 1100 miles and got 18.63 mpg. I keep a log to track gallons, odo reading, location, and whether or not I fill to the neck. Gotta admit, I was shocked so I recalculated over a few shorter intervals and they were all 18.1 to 18.6. 95% of that mileage has been 60mph unloaded miles, but still I'm pretty happy with it. It's my first summer with my 6.0, so I guess I didn't know what to expect.
 

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True Speed is an "ok" devise.

But if you want a better speed calibration unit...get a SPEED WIZARD.

The SPEED WIZARD is push button,...not a screw driver hole like the true speed, and it can be calibrated while in your driveway...not like the true speed where you have to be driving to calibrate it.
 

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I'm running 37's and have compared my factory trip meter to my trip meter on my GPS on many, many occasions. For every 100 miles on the factory odometer, I've actually gone 112. So I have a 12% error.

The GPS also gives you an accurate mph, so no need for a TruSpeed or a Speed Wizard.

--Snake
 

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first - thanks Tank's 250... the speed wizard does have two buttons and is the only speedometer correction device that will provide a user interface - the speedometer...

I'm running 37's and have compared my factory trip meter to my trip meter on my GPS on many, many occasions. For every 100 miles on the factory odometer, I've actually gone 112. So I have a 12% error.

The GPS also gives you an accurate mph, so no need for a TruSpeed or a Speed Wizard.

--Snake
snake... thats a good way to think about it however do not forget about maintence and when you go to sell the truck the milege on the odometer will be incorrect - just 2 cents the only way to correct the odometer is a trusped or speedwizard as far as i know or to get the abs module reprogrammed

kenny
 
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