hmph,
The STEEPEST grades are NOT in the rockies. NO interstate can be steeper than 7%. Now get yourself on a local grade, they can be from 0-mid 20%! We have some of those here in the greater seattle area on local roads.
What you have to worry about in teh rockies is ELEVATION! ie a non turbo/super charged/forced inducted motor loses 2-3% of its HP per 1000' above sealevel you get. So when on Eisenhower pass at 11Kft, a non forced inducted motor is down upwards of 33%! So following this logic, one should deduct 33% off the max trailer rating so you would have the same performance specs from the motor as you would at sealevel. This is why many folks like Diesels with turbo's!
Otherwise, there is no real reason to lower tow rating due to altitude or goign thru the rockies/yellowstone etc, I went thru with my 96 GM at some 4000 lbs OVER gcwr, I had no white knuckle issues!
Marty
