Speedometer help

So now that I got my tunes in, and it's working great, and I received the actual tune names from Longhorn, I'm on my way. However, about 5 years ago I installed a little larger of a tire on the truck. I now run 265 75R16's on it. The stock tires were so small for the truck. Anyways, my speedometer has always been about 2-4 miles an hour fast since then, depending on my road speed. I was excited to learn that I could adjust this with the AutoCal, and thought they had done it for me, but it doesn't seem to be.

I have v8 and v7.5 loaded on my computer and watched many videos and read posts on this, but can't seem to get to where I'm at now. I opened up the tuning file, named 0022.ctz (in 7.5), and entered in my new tire size, and the numbers definitely changed in the right direction. I saved it as 0023.ctz. Now, how do I get it to the AutoCal device? I can't seem to find out how to get it there. When I look at the AutoCal unit itself, it has either Prog1 (DSP5.ctz), or Full1 (DSP5.ctz). I also can't seem to find DSP5.ctz on my computer. It also prompted me to plug in my AutoCal device, but it already was plugged in! Not sure how to get the 0023 file to the unit so I can reflash, and keep the tunes that I already have loaded.

Help?

UPDATE—found the DSP5 file in EFlive explorer. Copied it to my desktop. Looks like the 0022.ctz was a read file under the tune name DSP5. When I tried to open DSP5 in V7.5, it said it was flagged as private and gave them I used V8 (which I have). When I open in V8, I get a screen that there are security restrictions active, and the calibrations cannot be viewed or modified.

You would need to ask Longhorn to provide you with an updated tune file. Even if you could modify your existing tune, in order to flash it with your AutoCal it MUST be saved with Longhorn's FlashScan V2 serial embedded (which only can happen if they save it).

AutoCal gives users the ability to flash tunes written and secured by a particular tuner. It does not give end users the ability to modify tunes. AutoCal also prevents end users from switching tuners unless the original tuner chooses to release the device.

Only the tuner who