Denver to SLC: us40?

I assume there's a really good reason, other than you just like the punishment. I lived quite a few years in Co. and had to check the map to find US 40. Can't imagine anyone choosing that route unless he had a powerful urge to see Steamboat or Craig.
Otherwise, I25 to Ft Collins, US 287 to Laramie, jump on I80 and go trucking.

 

Agreed, most roads in Colorado west of I25 will take you in the mountains and they are not truck friendly. I don't think I70 is truck friendly. Good Luck.

 

US40 west of Denver starting at Empire CO is kind of truck friendly all the way to Steamboat Springs by saying that the roads are nice and not too narrow (Exit 232 on I-70). It is a very scenic drive if you have a little extra time. There really aren't that many places to pull a truck into on that road for things like bathroom breaks and food. You may find a spot here and there but nothing like a truck stop. If you take this route there is a Kum & Go gas station at Kremmling that you can park on the side street next to it if you need a drink or a bathroom break.

 

Truck friendly, 25 to the 80

 

It's an Ok drive at under 50k. I would not want to run it over 65k unless I had to. I can appreciate wanting to take the opportunity (lower gross and time to burn) to see some other stretches of road that you may never get a chance to run again.

Give Rabbit ears pass (western drop) some respect even at 50k

Some guys just don't get it.

 

Back in the day, late 80's we hauled beer out there and had a driver run 40 from Rabbit Ears to I-70, said from Winter Park to I-70 was a challenge and he drove a Cabover with a 48 ft.van, said that he would not do it again, even the CMCA advises not to run that way if you do not have to, maybe that changed. I ran to Steamboat Springs often and would run I-70 to Silverthorne then 9 north to 40, if you go that way you will have two big downgrades to deal with, Straight Creek Canyon just after the tunnel and Rabbit Ears Pass before Steamboat, I ran those two with out a jake and grossing 78-79,000 you will be fine with that. I would still take it easy on those to grades. From what I remember 40 from Rabbit Ears to Salt Lake will be a breeze.

 

While there is only about 5 miles difference in the mileage. The traffic is what will get you.
It is the height of tourist season. Get behind an underpowered vehicle hauling a too large travel trailer and you will see your average speed drop dramatically. Add to the fact there are not a lot of places for you to stop when your 11 hours is about up and then what?
25 to 287 to 80 is a 9 hour run. I'd rather save the hours driving for another day. Save the scenic driving for vacation in your POV.