I-70 W of Denver

The Interstate hiway system was build to a standard where the maximum grade is 6%. There were exceptions granted for sections of the hiway that existed prior to the establishment of the system but which became part of the system. The steepest grade is 8% and is on the westbound lane of I-24 in Tenn.

Not that steep, IMHO. Major interstate highway, lots of big-rig traffic, so you should be ok.