Where are the steepest longest mountain grades? I just got home from a trip out west, I hit Raton pass into NM. Up thru AZ into CO and to SteamBoat Springs and over Bunny Ear Pass???Is that what it's called? Then back to I-70 and over the Rockies to Denver. The old Dodge just pulled them all. Boy does it smoke when the air gets thin.

 

It's really called Rabbit Ears Pass elev. 9426. The rock formation near the top lends itself to the name. If you travelled on any Federally funded road such as an Interstate or a US highway, the grades can not be more than 7%. That's still plenty steep. By the way if you went through the Eisenhower Tunnel on I-70, you went through the highest vehicular tunnel in the world at 11,158. ft. pretty thin air there. Sounds like you got to see some very pretty country.

 

East or west out of Bullhead City AZ are pretty steep, and the 120+ ambient temps in the summer months don't help anything either. I believe the east pass you go from 500ft to 3600ft in about 12 miles. Another loooonnggg never ending grade is I-80 out of Salt Lake toward Wyoming.

 

Pulling the grade from Apple Valley to Big bear in California is over 18 percent and several miles of switch backs. One time I pulled that win an Astro with 6v-92 loaded with railroad ties. Gross over 84,000. I never did that again..

 

You did see some pretty country. We have one down here on I 25, about MM 100 thru La Canada pass or maybe its King canyon, That looks like it's more than 7% for about a mile. Every time I pull a heavy load thru there I bog right down. The hill on both sides are full of black tire marks going all over then into the side or median. Many of them are from smaller vehicles pulling a regular tt. Rare do I see a 1 ton with a 5er on it's side there. There is a lot of pretty country out here in NM. I've only been here 3 years, but I love to explore the mountains.

 

7 or 8% grades for 10 to 15 miles is the usual thing out here. That's what the Cummins and exhaust brake are for. Nice to have that huge radiator too.

 

Carson Pass in CA is a long, winding and steep grade but I don't know the average steepness. There is a fairly short section that is 28 degrees. This is not a main transportation route but I have been surprised at some of the rigs I see there. I have to take it in second gear on the steep sections when I weight 12K.
Not really what this thread is talking about but a kick to drive, as long as the truck and brakes are in good shape.

 

St helena over 29 in california i think has a few spots in the 18% grade with a sustained average uphill of 12% @ 6 or 7 miles up and its the same off the back side.

White bird pass was always a good long one 7 or 8 miles at 8% with a section at 10%. The old white bird was all switchbacks alot nastier........and is still there. if you are good with not using your brakes and just compressioning down a hill it makes for great entertainments with a trailer and the girlfriend sitting in the passenger seat looking off the steep side of the hill all the way down.

down side you get slapped a few times

Colorado, multiple grades especially on the two lane state highways. california the north coast highwya 1 is nasty so is 299.

Dropping into jackson hole is a good one too. Also rogers pass on 200 in montana on the east side of it can be nasty, steep and tretcherous when icy

 

Been up that hill many, many times. Use to go camping up there.

Rich.

 

In the above post I said Carson Pass when I really meant to say Sonora Pass. Sorry if it caused any confusion.
Raften

 

The steepest grade on the Interstate freeway system is in Tennessee going over Monteagle Mountain on Interstate 24 Westbound. It's 8%.

 

I remember coming down the south side of monteagle in a brand new ford ( I know so dont start, it wasnt mine) ranger. It was me and a friend of mine ( his truck) and my girlfriend at the time. We were in one of the center lanes and traffic was backedup on all the other lanes. I hit about 120 coming down the mountain. My friend was sleeping in the bed of the truck and I was driving. He said he heard the caltlytic converter popping and raised up and started beating on the back window for me to slow down. All I did was point behind us. He turned around and looked and laid back down. There was a fully loaded 18 wheeler about a 1/4 mile behind us and he was gaining. I didnt have another lane to jump into as they were full and backed up.


Now that was scary.

 

We don't have the very long steep grades in the east but we do have some hairpin turns.



Our recent trip

 

Highway 120 from Yosemite Junction to Groveland up priest grade and on to Yosemite Valley is a handfull to drive with CTD and a 12K 5er.

Marc

 

Dan Tana that looks like Deals Gap.