2004 sedan, 5AT @ 70mph= 2400rpms. At 80mph=2950. Since I have oversized tires, my actual mph at 70 is 73mph, at 80 it's around 83.2 based, on gps.

I also get around 450-500 miles per tank, combined city/highway. Gas pricing are climbing quickly and are at $3.35 for 93, or $3.10 for 87.

 

What size tires do you have? Any mods?

 

What size tires do you have? Any mods?

 

Yeah..my speedo is off by 3-4 mph according to the GPS. I just figured it was off due to the smaller tire. Thanks for all of you help..I just wanted to see what was going on. Guessed these thinks are geared for goin fast!

 

I switch between 245/55/17's (rear) and 235/55/17's.

No mods--- that's a guy thing mostly.

 

245 rear and 235 front?

 

Rears only. Not sure the 235's would fit on the front, but will find out on my next tire change.

 

Most production cars read a few mph faster than they are really traveling. It is a liability issue. It would be a big liability if the cars were actually traveling faster than the speedo indicated. If that was the case the OEM could be sued for accidents and tickets. As a safeguard against this they err on the side of over-stating speed.

Now if the speedo reads a few mph slower (from the factory) that would be remarkable.

Dyno's can also measure the actual speed.