Wow - having a warm spell! It was almost that in southern CA and AZ.
No spare as is somewhat common these days. To big and heavy for me to change anyway and with a 20K lb axle the equipment would be big and heavy.
I'm not worried about a flat in terms of delay. If I can't find lots to do while waiting then I probably shouldn't be going to Alaska.
While a flat is a non issue a blowout and rig damage would be a concern.
Meet a guy that bent his fiver hitch (likely didn't slow down), spent 19 days in Dawson Creek and continued on with the trip.
Meet a guy in Fairbanks with a 10 day delay for repairs. His caravan tour left on schedule without him.
Meet a guy in Haines with a engine valve issue. After many days on the phone and email the bottom line was ferry to Port Hardy and tow to Victoria for authorized Cummins repair. Lucky guy as I'd love to take that ferry trip with my rig and get off at every stop! :B
Stuff happens!