Some have been posted before, some have not. (maybe)
Here are some of the many links where to get answers about towing and vehicles in general. Feel free to add your favorites. Some are for newbies, some are for everyone.
TOWING A TRAILER NHTSA guide online, Being Equipped for Safety (PDF Version 284K)
" Product Guide for Chrysler-Plymouth vehicles...." a lot of clear explanation of terms, simple drawings. Good for beginners, subjects like: "Specifying the Proper Vehicle, Types of trailers, Trailer Hitches, Safe Towing Tips" all about those GVWR, GCWR,.....
ANALYSIS OF THE IMPACT OF SUV IN THE U.S. with fun things like: Tow Ratings for Selected 1999 Models (cars, pick-ups,vans,SUV...), and Fatalities in SUV-Involved Crashes, 1980-1998, by SUV Size Category
Tow ratings (PDF files for model years 1999-2003 ) from Trailer Life
RV and Tow Vehicle Weights: an exercise in reality GM trailering & GVW info Physics of Automobile Rollovers
you can go directly to the punch line, or look at the nice color charts. You may even enjoy calculations of the type:
v t = 0 2 = g [ r + t 2 ( 1 - cos ? ) + h sin ? ] t 2 cos ? - h sin ? h cos ? + t 2 sin ? + 2 g [ h ( cos ? - 1 ) + t 2 sin ? ] (a lot of the greek letters don't show up in my text)
Engine Performance Degradation about the effect of altitude on engine performance. (it's about pop-ups, but a lot of interesting things about towing in general)
Quick Links
Some more links about towing 
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