I have a 2003 1500 hd. I bought it with 285/75R16's on it. How bad is the speedo, tach, gearing, driver's infomation center reading off? Will a tech-2 adjust the tire hieght or do i have buy a programer? Thanks fo the help!

 

anyone out there?

 

i dont know but that tire is the same thing as a 33x11.50R16

 

Assuming the stock tire size is the same as the '02 1500HD I had, 245/75R16.

Your speedometer is reading 7.782% slower then you're going.
The speedometer reads 55.6mph when your actual speed is 60mph.
Here's a link to a pretty good tire size calculator.
10-10 tire, tire size calculator

As far as I know a tech-2 can correct for tire size, so can programmers or tuning packages. The tach shouldn't be affected by tire size. The DIC will think the speedo is right and all your fuel mileage numbers and anything related to distance will be off, unless the previous owner had it corrected for that size tire already.


There are a couple of easy ways to check the speedometer.

If you have a GPS or could borrow one you could compare speeds.

You could compare to a car that's known accurate.

Cruise around until you find one of the police speed monitoring rigs. (Alternate method involving the police: Find a speed trap, get ticket and compare to speedometer reading.)

Or just do the mile a minute thing with highway mile markers, cruise at 60 for a few miles, if it doesn't average 1 mile a minute the speedometer is off.

 

i like the get a ticket way lol......

 

the tech-2 did do that tire size!