I have a set of 17x9.5 rims right now and i going to get a new set of C6 zo6 18x9.5, and i have a mailorder tune. i wanted to know if it would [EDIT] up my computer to use my old hypertech programmer to change the tire size for the speedo

 

probably yes

 

yes it will mess something up or yes i can do it

 

It will mess it up.

 

Do you know who the mail-order tune is from? You can always call or email the vendor and find out for sure what you can and cannot do with your PCM.

 

Right just have the mail order tune adjusted otherwise youll have a worthless hypertech tune.

 

i havent had that much luck with the vendor, he been helpful but , i just want to adjust for tire size not us the hypertech tune, i just want to know if it will erase the mail tune

 

I'm guessing here but the hypertech asks you if you want to use the tune...just hit no and go to the tire adjustment section...as long as you don't tell it to program the comp it shouldn't...I think you should be fine IMO...but I am no expert and could be wrong...

 

see that what i think if i dont use there tune it wont erase the mail tune, right

 

Unfortunately it's quite probable that doing anything with the hypertech after getting a custom will screw it up.

http://web.camaross.com/forums/showthread.php?t=406064

It seems to work for some but not others.

 

That is correct. Some revisions did not alter the tune and others overwrite it. Either way, it's a bad idea to combine the two.