#### Andyinchville1

##### Veteran Member

Hi all,

I went from the factory size tires at 195 65 r 15 to

205 70 r 15.

Based on my GPS my speedometer is now more accurate Speed wise but how does that affect my mileage calculations?

I have read that the factory speedometer reads a little on the fast side relative to real speed and upsizing the tire makes it the speedo correct but I think the odometer was set to read correctly with the factory tire size ..... so now the odoneter is not correct?

so now that I updated my tire size I think I need to use a fudge Factor when calculating my mileage...

I'm not sure how my friend calculated it, but I think my fudge factor is 5%?

Meaning I take my miles and / gallons to get miles per gallon and then multiply that figure by 1.05 to get my corrected miles per gallon does this sound right?

Thanks in advance for any and all help

Andrew

I went from the factory size tires at 195 65 r 15 to

205 70 r 15.

Based on my GPS my speedometer is now more accurate Speed wise but how does that affect my mileage calculations?

I have read that the factory speedometer reads a little on the fast side relative to real speed and upsizing the tire makes it the speedo correct but I think the odometer was set to read correctly with the factory tire size ..... so now the odoneter is not correct?

so now that I updated my tire size I think I need to use a fudge Factor when calculating my mileage...

I'm not sure how my friend calculated it, but I think my fudge factor is 5%?

Meaning I take my miles and / gallons to get miles per gallon and then multiply that figure by 1.05 to get my corrected miles per gallon does this sound right?

Thanks in advance for any and all help

Andrew

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