Actual tire size changes not working i1000 Pontiac Trans am

[rlnewman]

I made changes to the actual tire size parameter for the rear tire size.
Thought the programmer put the changes in the current custom tune
Went for a test ride and speedo is way off very fast.
So came back to check the tune parameters and found the
Actual tire size marked as changed, but the tire size was not in the I1000.
The only thing that was set was the tire height at 36 inches.
My rear tires are 26.5 inches. Speeado way off.
So tried several times to change the tire size and the height but
each time the parameter stayed at 36 inches and did not
accept my change.
How can I remove the parameter for the Actual tire size parameter or get the
programmer to accept the size of my tires.

Speedo was not very far off before I made this change.

first problem I have had with the I1000
I have a custom tune for engine change n the I1000.

Please help I know I am not going as fast as it says.
Thanks for you help.
Rich Newman
217 725 9493

[mikel]

it may default to 36 but thats not what it is writing if you chnage it to a correct value.
Are you setting it to 28 or so?