Calc. MPG with bigger wheels

[kcryan]

So on my I30, i know that the speedo reads 4.5% too slow with my summer tires on, if i take the miles traveled on one tank, multipy it by .45 and add that to the originally listed miles, then divided by the gallons would i have correct MPG?

Thanks guys

 

[Vilan]

4.5% would be 0.045, not 0.45. But the rest looks good.

 

[Matt_S]

You can also just multiply the listed miles by 1.045 and save the addition step.

 

[mechtech]

The speedometer may be off, but the odometer may be right, or visa versa.
Check the odometer against several road markers on the highway.

 

[surfstar]

quote:

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Originally posted by mechtech:
The speedometer may be off, but the odometer may be right, or visa versa.
Check the odometer against several road markers on the highway.

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Agreed. Or a GPS. I'm running 195/60/15 tires on my car which originally had 185/65/14 and the odo and speedo are within 1% accuracy (vs GPS) despite the 3.2% difference from stock size.