eggie

With my tire size (205/45 on 16" wheels) my speedometer is 5mph fast. Which also means higher rpms. which means low mpg, no much I am sure, but mentally I know it is something.

For example, I am cruising 70, really doing 65. RPMS are at 3500, when they should be at 3100ish. 80 @ 4000 is really 75@3500ish, etc...

Ford, GM, Chevy and some Toyotas have aftermarket equipment to plug into the OBDII and can adjust for tire size changes. I have yet to see anything for our vehicles.

Anyone have suggestions? Dealer won't do it.

dexter_5000

205/50/16 tire will correct it.

eggie

And cause more rubbing and has nothing to do with speedometer recalibrating.

dexter_5000

i had no issues running that size on my xa with coilovers

IH8ONYU

there is no way to recalibrate the spedo.. you can move the needles to get a truer reading of your mph, or go back to the proper size tire / wheel combo, or live with the issue, knowing your rims and tires are pimp... there is always a trade off when it comes to pimp looking $hit...
If the dealer could recalibrate they would, but they have no way to do it..

jct

buy scangageII and use that as your speedo

TheShortBus

^ what he said. Use any GPS to establish accurate speed, and the ScanGauge has capability to + or - its reading to match GPS. Presto--your Scangauge now shows accurate MPH with current wheel/tire setup.

If you use a different wheel/tire setup for winter (like I do) simply repeat the GPS/ScanGauge calibration for the NEW setup. Again, use the ScanGauge as your speedo, since it will show true MPH.

eggie

None of these help, except the it cannot be done answer.

I can use my TomTom if I wanted and I already know I am 5mph slow.

The problem is the rpms. The rpms don't match the actual speed so I am actual spinning the motor faster thus using more fuel.

richmond2000

the RPMS has NOTHING to do with the speedo because the engine is running faster because wheel / tire combo is smaller diamater than stock........... you have effectively changed your gear ratio