I would never travel in/around Alaska without a spare. The last time I was there I blew 3 tires on the RV in one trip. Of course that was 1965 and the Alcan Highway wasn't paved yet :-).
The "Gravel" in Alaska and the Yukon Territories seems to have a lot of shale in it. Those little flat chips of shale get wedged into the tread and then just dig and dig and dig until they even get through the steel belts.
You might think - "well, I'm not driving on any gravel roads" - but you will pull into campgrounds, parking lots and other spaces paved with Gravel.
Last time I drove up that way (2008 I think) I talked to some locals that told me, "in the winter we run really expensive steel belted snow tires - in the summer we run the cheapest junk tires we can find and always carry a plugging kit and an air compressor."
Buddy Ray - Atlanta
Jayco Eagle HT 26.5RLS
Ford F150 Lariat, 3.5L V6 Ecoboost
Max Tow Pkg, 36gal tank
Reese Sidewinder and Reese Titan 16k hitch