towing

["John Proudman GGPL B-262" <johnp@lpsi.barc.usda.gov>]

Dyane,

I have an F-150 (1991) with a 350cc engine and tow a steel two-horse 
gooseneck with tack room, 4500# empty according to the manufacturer.  
Probably 6500# or more loaded.  It down-shifts on ANY but the slightest 
grade, even ones that you would hardly notice in your car.  I would 
probably not be passing you on a 7% grade, even though I am towing less.  
 The GCVW of the truck doesn't matter so much as the size of the engine.  
A 7% grade is pretty steep, and the engine will work harder at 4,000 ft 
than where they determine those GCVW figures.  If you add two horses, 
tack, and equipment to your trailer then you are probably towing well 
over 4 tons!  You need a diesel or very large gas engine to move this up 
a 7% grade at anything close to highway speed- regardless of the GCVW 
rating.  If it is rare that you must climb a grade like this, then resign 
yourself to lugging to the top at a slow speed and keep your RPMs 
reasonable.  If your truck spends a lot of time towing in low gear/high 
RPM, then I would worry about overtaxing the engine.  I'm afraid the only 
solution for this is either less weight or more engine.

John