Odometer Question...

[jjcool00]

So here's a weird scenario I encountered this weekend. I know bigger wheels throw the speedometer off but has anyone seen a case where it throws the odometer off as well? The reason I ask is because now that I'm moving I spend every weekend driving up north to apartment hunt. When I plugged the address into my GPS it said it was 243 miles. However, when I reached my destination my TRIP said I travelled 260? I took no alternate routes and reset it as soon as I started. Maybe my GPS is wrong? Or are the bigger wheels actually contributing to me driving adding phantom mileage to my car?

 

[joegr]

Yes, how could it possibly effect that speedometer without also effecting the odometer? They are both using the same speed pulse signal. There's no magic here.

 

[jjcool00]

I guess I didn't realize that would be one of the disadvantages to going with larger wheels. I never plan on selling my car unless I get an offer I couldn't refuse but if I had known id be devaluing it more than I already am I probably would've never gone with bigger wheels. Thanks for the response, Joe.

 

[LS4me]

Shouldn't it work the other way around? A bigger wheel rotates slower than a smaller wheel so actually travels fewer miles. correct?

Use a tire/wheel calculator and try and stay within a percent or two of stock.

 

[jjcool00]

I have no idea mathematically how it SHOULD work, all I know is that somehow approx. 20 miles got added to the odometer.

 

[oddball]

IIRC, the dealer can reprogram your PCM for the new final drive ratio.

 

[LS4me]

I have no idea mathematically how it SHOULD work, all I know is that somehow approx. 20 miles got added to the odometer.

I've noticed a discrepancy between mapquest, google maps and my NAV between destinations, using the same routes; though not THAT extreme. Weird........

 

[FDR]

Could the GPS have rerouted to a faster but longer route mid trip?

Yes, a larger wheel makes fewer rotations for a given distance, meaning fewer miles recorded by the speedo and odo. Your speed will be higher than what the gauge reports. You also lose a minor amount of torque

 

[jjcool00]

As far as I know it didn't do any rerouting. The trip was supposed to be 243 and when I got to my destination it was over 260. I have 19"s. I'm going to make the same trip this weekend so I'll check to see if it does it again.

 

[joegr]

Get on the intersate. Zero your trip odometer as you cross a mile marker, then see what it reads at the next mile marker. If you can, go ten miles to get a more precise reading.

 

[LSV8FAN]

If you have a smart phone, you could download apps that you can use to compare speed and distance traveled using gps. For my Android phone I have Car Dashboard, which shows speed, altitude, direction, local temperature and time; I don't think it has an odometer function. Another app for Android is GPS Odometer, this one will give you distance traveled and average speed.