Save your money. Alaska is part of the United States and IMO, has better roads than many of the northern lower 48 states. We have driven thousands of miles on roads in Alaska and "NEVER" had a need for multiple spares. Now, that said, there are a couple roads that I would not drive, because of the surface composition and those roads have shuttles that you can take.
The key to travel in ANY northern state or province is drive the appropriate speed for the road condition and get as far to the right as possible for oncoming big rigs that are probably traveling way to fast for road conditions.