US 89 Grand Canyon

I think commercial trucks are prohibited from all national park roads.

 

I enjoyed running up from Flagstaff to I70 up 89/160/191 when I took a load from Phoenix to Denver.

 

Park your truck at Little America in Flag, then take one of the shuttles that runs to the Grand Canyon.

 

Lots of parking at Page, AZ by the bridge. A few towns along the way have truck facilities. It's a nice drive.
I seem to remember 89a had some kind of restriction on it from Bitter Springs to Kanab so I never took that stretch.
I used to cut over 20 and come out on 15 just south of a Beaver.
I actually got to take a load of oats for the pack mules right into the Grand Canyon, even got to travel in via the East Gate where no trucks are allowed. But the farmer that brought in the hay and ordered the oats had permits for over thirty years to come in that way.
He had the Pete with the hay, my truck had the oats in the van behind him.

 

I think the canyon is 90 miles off route.

No restrictions along the 89 route. There's a few dirt pull offs between flag and the state line. Not much in utah. Kanab is the only real town. There are 3 towns after kanab but not much there. Panguitch be the next town. 10 miles after is the 20 over to the 15 hill. I've gone past the 20 only once and taken that route. It's a windy slow going road. Not much there either. Goes up to the 70.

Any detour you take. Is going to add some miles and quite a few more hours to your trip. The roads may also be narrow and not truck friendly. the 89a over the mountain to the lake is one of them. Drive during the day isn't bad. Not much fun at night.

Your only construction spot last time i was there. Camerons Corner. They've installed a roundabout. And now there changing up the road to be a divided highway.