ok so saturday i discovered my speedometer is off. its good up til 25 then until about 70 its about 5 off then after that its like 10 off. what to do? its an auto

do you have different size rims or tires than stock?

Did you ever change the diff with one that has another ratio at anypoint or something?

i have the same problem on my fone dial rims...i drove from NC to Portland and it was a 3000 mile drive and my odometer registered 3300 miles. The other day i was driving by the lil speed display of how fast i was going and my speedo says 40 but the display tells me im doing 36. I say im about 10 percent off so i just calculate that in, but is there any reason for this?

different size tires than stock? bigger smaller?

If you rims&tires are of a smaller total dia. you will read a faster speed than actual speed (ie your speedo will read 65 but you will be doing 60) you will also get a greater amount of miles on the clock because the wheels are turning faster and the count is going faster. if you have the stock size rims and 2 tire sizes smaller you will be .2 off per mile. It will add .2 miles per mile and you will be about 5 mph off. hope that helps out on that question...Or your speed sending unit might be taking a crap.

everything on the car is stock

If it's an auto tranny, I'd suspect the little gear inside the tranny that goes to your cable is worn causing it to be thrown off. Of course, it depends what type of transmission you have if it even has one of these. I'm guessing yours is also electronic so I'm not sure if that uses the same thing I'm talking about.

what tires are stock for the fone dial rims?

dont trust those things, they are very inacurrate.