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Discussion Starter #1
I had 4:10's put in the rear end the other day. Today I changed the tune using my Xcal2 to 4:10 gears. I pulled out my GPS to check the speedometer and its way off, Going 45MPH my speedo says Im going 95, its off big time. I noticed I can change the tire rev, but I didnt, I cant find the info need on my tire (goodyear Eagle F1 285/40ZR18) But no matter what the tire size is it shouldn't be that far off....should it? I hope someone can help me before I get a ticket
 

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That's strange. I would try it again with the tuner. even with tire size, it would be off a few mph but nothing like what it's doing now.
 

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Discussion Starter #3
I fixed it, I set the wheel rev to 750 it was at 500. its off only 1 MPH.
 

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Discussion Starter #6
My Xcal goes from stock, 500, 505...all the way up to who knows.....But 247 I could'nt put that in if I wanted too, but 750 is correct for my car
 

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