I just thought of this... If you buy a programmer cant you just program in that you have like 15inch wheels or something and if you really have like 26's cant someone fake mileage or something.. i mean is it really that simple?

No. Its illegal for one to alter your odometer. Not to mention the memory of the mileage is not even stored in the cars computer but actually in the instrument cluster itself.

I know it is illegal to alter mileage.. however I was reading all the features that the programmers come with and they say you can change your tire size.... so if you add a bigger wheel/tire it will compensate so the mileage and speedomter will be accurate.. i just started thinking that wouldnt it be possible for someone to go an program in that they are riding on like 15's or whatever the smallest wheel that you can input in is but really be riding on a bigger wheel.. so the computer will be programed that you are riding on 15s and so when you are really doing lie 60 its only reading 50 or whatever.. im just saying that couldnt someone just trick the ocmputer like that?

On an '01 Denali, I had a Hypertech programmer that I bought to reprogram my tire diameter. It basically allowed you you change the diameter setting from 22" to 28". The typical GM Suv tire is 25.4 to 26" in diameter.

I set it to 22" for fun, thinking I could make the miles move more slowly, but every few minutes, the on-board computer displayed an error (by number). This requires using a ODBII reader to figure out, so I just changed it again. It was happy with a diameter of 24" or more.

The thing I noticed though is that the shift points didn't seem to be optimal for the amount of acceleration you were expecting, using the smalle diameter. It held onto the gears TOO long, which could not be tweaked with.

I had bought tires with about a 1/2 smaller diameter, but wider, and I didn't want to overstate the mileage, so I bought the programmer.

It allowed me to program it for premium fuel (more spark advance), harsher shift points, longer holding of gear before shifts, tire diameter, and a couple of other things I don't remember.

Dave

The Hypertech does not fool the computer nor changes the revolution reading on the speedo for say 15 inch tires. It corrects the reading for tire size since your speedo is reading incorrectly with aftermarket tires.

The typical GM Suv tire is 25.4 to 26" in diameter.


Since when? Envoys and Trailblazers tire height is around 30". On an 2001 Denali its a minimum of 31" most commonly closer to 32".

Even in the 80s and 90s with a 235/75-15 the tire's height was still 29" or more.

Sorry, your right. I was daydreaming.... I think the max was 36" on the programmer...

Dave