Yeah, I'm not sure. It's probably in the manual somewhere. I was also thinking of deflating the spare to 41 lbs, make the differential 6.
That tool's only like $35 on eBay. At that price point, each member should buy his own! But honestly, the truck should have come with it. I think the SuperDutys do. To me, holding that little device by each tire makes a helluva lot more sense than letting air out, while waiting for a honk of the horn. No shit, that's the instructions in the manual ... Get into learn mode and start letting air out until the car beeps. F-that.