2007 Chevy Tahoe tire size Q

[nath]

Hello all,
I have a 2007 Tahoe and I love this Programer!! A quick question, I like to effectively reduce my gear ratio by programing in that my tire size is larger than it really is ie. I have 285/70/17 and i tell the comp that I have 305/70/15 and it essentially lowers the ratio, I have more torque, quicker off the line, shifts are sooner, etc. I know that it throws my speedo off by about 3mph but I do not mind, now to the question. Am I causing any trouble for my truck by doing this, aside from the speedo being off of course?
Thanks in advance.
Nath

[mikel]

you are not making any more torque by tricking the speedo...I promise.