http://forums.maxima.org/showthread.php?p=5950689

cliffs: gps showed diff readout compared to speedo

Are anybody else's gps so far off from their speedo like mine?

Jae

 

Ya the speedo's inaccurate. Esp if you're not runnnig oem sized tires/rims.

 

Yeah my Alpine NAV info said my top speed was 230 MPH when I've only gotten up to 95 MPH recently. I'll take a pic and post it soon. But my actual speed is pretty close give or take two miles. Bigger wheels don't make a difference the GPS is going off of satellite position, not the gears in your transmission.

 

That's a good point. Thanx. LOL, u were going 1/3 speed of sound huh?
Jae

 

Bigger wheels won't make a difference, but larger diameter TIRES will make a difference between your speedo reading and the car's true speed.
with 255/45/17 tires, my speedo was within 1mph of my GPS up to 125mph.
with 235/45/17, my speedo reads about 6mph fast at 100mph.

trust the GPS, not the speedo-- except when it's telling you you're going 230mph or som**** like that.

 

i run 245/40-18s and get a 1-2 MPH difference around 80. i heard that most speedos are designed to be about 2 MPH off which i guess can be a good thing when it comes to the popo's. also, it will be slightly more off as u wear down ur tread vs when u get new tires put on. obviously, larger tires than stock will affect it as well