Speedometer error

[cobra_1]

My speedometer seems to be off by quite a lot. I have 245/45 tires on stock 17" rims. According to the GPS the speedometer is off about 4 to 5 miles per hour slow. Is this common? Most car I have had the speedometers have been close especially with tires close to the recommended size.

Next question, can this be fixed by the computer?

Thanks

 

[nearlyhalfamile]

Your speedo should read 2.2% to fast with those tires, so depending on speed it can easily make it a few mph off. A programmer should be able to solve this issue.

 

[gcwimmer]

A tuner and with Xcal you can set the tire circumference or a Lincoln dealer.