If you listen to Gene's advice even thought it might work...
It might end up costing you money in the long run!!
(those darn tires went from a $700 set to a $1700 set in about a nanosecond!)
Back to the subject now:
Well with our 17" rims the 315 is a 35". Ok I'll restate that. Go with a 285 or 295.
Oh yeah and jacking up the truck to get the blocks in is a good thing. Let that be a lesson to you!! Having the truck blocked and raised in the rear will help you maintain proper pulling geometry (did I just say that?) while pulling.
Keeps the truck going downhill!
(watch video #2 in my sig to see what I am talking about).
In your video your truck was going up hill the whole time which is a no no.