Despite HPK's detailed reasoning for not buying the book or books, I suggest you check out the Mountain Directory website and make your own decision as to whether to go around or over a particular route. You're the only one that knows your level of experience and whether or not you want to test it in places like "Oh My God" hill on 14A in Wyoming. The East directory may not be as vital as the West, but the grades are still around - just not as high or as long. Both books are available as hard copy or EBooks now.
Retired and visiting as much of this beautiful country as I can.
IMO, as a flat lander, the mountain west directory is a valuable resource. We refer to it every time we venture into the mountain states. It helps us decide whether to take a particular road and if we take it, what we are facing. We would not be without it, but you have to decide your comfort level is for driving mountain roads.
I have used the Mountain Directories for several years and find them extremely useful. The information on passing lanes, speed limits, switchbacks, length limits and warnings about taking large vehicles on a route is pretty straight forward and self explanatory. The references to grades in % and altitudes takes some perspective based on experience and the capabilities of your particular vehicle to know the difference between climbing or descending a 5% versus an 8% grade and climbing to 10,000' versus 7,000'. Once you have some reference points for comparison, the descriptions in the directories provide a pretty accurate prediction of what you can expect on a route.
I bought one because every one said oh you have to get one. I looked at some of passes I have been over several times had a big laugh, tossed it in a cornor somewhere and unless my wife did something with it its still there. If I had the book before I had alread been over some of the pass I may not have gone. If its paved, has a state or fed road number and there isnt a sign RV's should not use then Im very likely to take it
2000 Ford F-350 SRW 4X4 PSD Jayco Super Lite 29.5RKS (31') 5th wheel 50 gal X-ferflow in the bed tank. Banks big exhaust and Stinger kit.
Knowing that long 6% grades at altitude are not friendly to the heat gauge for my transmission, I used the Mountain Directory West to avoid three of them in one day in Mt this summer. By selecting another route I only added about one hour to a day trip.
2001 2500 Silverado LS 4x4 6.0, 4.10
2007 Jayco Eagle 288RLS
Cocktails for 6, Dinner for 4, Sleeps 2
End of dirt road, no signs in sight, sun going down: I am not lost, just getting ready to go camping.