I have seen the maximum grade % for interstates is 6%. But is there a set maximum for US Hwys and other roads?

Is there a listing of % Grades for different Hwys in the country?

 

For interstates it is 6%, but for mountain passes quite often you'll see 8% and as high as 10 or 12% for short periods. Haven't seen a list but Diesel Power Mag did an article on the top 10 toughest hill climbs in the US recently.

 

That would be cool.. a nice gps feature for drivers maybe?

I would love to know what the grade on I-81(i believe) in northern VA was I pulled earlier this summer.. only hill I had to shift out of 5th gear for and it hated running wound in 4th for how ever many miles it was 6? 7? idk..

 

Reason for me asking is...

because I have been on the interstates around Central Alabama and Georgia and have not had any issues with pulling hills...never even loose speed in 6th gear.

This weekend we took a trip up US Hwy 280 between I-85 and Birmingham and I had the throttle Wide open alot to maintain speed in 6th gear(65-70 mph)and lost 10mph on some of the hills with the throttle wide open. Just guessing I'd say the hills were 10% or greater. Not very long hills...maybe 3/4 of a mile for the longest. Camper around 10K lbs and truck is a Stock F-350 7.3L dually with manual trans. I did have some firewood and other stuff in the bed (guessing 400 lbs), about 500lbs for occupants, and full tank of fuel.

I guess this is a 3 part question

1) are there grade maximums for US Hwys?

2) is there a list of Hwy grades (maybe something truckers use)

3) does this towing senario sound about right for my stock setup?

Also...i dont have gauges so I'm not sure what my EGT's were. would yall suspect they would be too high since I'm stock (at the moment)

 

Yes, 10mph loss on a 10% grade is not unreasonable at all. Had you accelerated from a stand still with that load, I would be willing to bet you may not have broken 50mph. It takes significantly more power on grades above 8%.

 

ya'll ought to try pullin Mont Eagle in Tennessee or Saluda mountain right there at the NC/SC state line on I-26. I know there's a lot longer and harder to pull grades out West, but as far as the East coast goes they're pretty stout. Then there's Sam's Gap on I-26 comin from NC into TN or vice versa, it's a pretty good pull on both sides.

 

Fancy Gap I 77 North Carolina, Black Mtn I 40 In NC these are good one to.

 

Fancy gap sounds familiar... might have been the one I struggled on... i can't remember the route I took but looks like I might have

peaked my interest.. now it's gonna bug me, to google earth I go! pretty sure we took I-81 (harrisburg pa to mobile al)

 

fancy gap use to be a hard pull for me with my 91 dodge and my 31 ft camper. so much easier with 08. fancy gap is on 77 north leaving nc going into va.

 

fancy gap is listed at 4.5% max grade

I81 by christiansburg is what i'm looking for is not listed oh well.