In Championship off road racing there are a number of different truck classes. The Pro Lite class must have a minimum weight of 2,800 pounds. The Pro class must have a minimum weight of 3,400 pounds. These weights would likely be representative of off road truck weights.
You'd have to narrow your criteria. Dump trucks can be anything from a Class 3 truck (such as a Ford F350) all the way up to off-road quarry trucks capable of grossing more than 80 tons.
4 wheel drive trucks are designed for off road use. Always practice safe driving be it on or off road.
It is an off road package for GM trucks
Off-road diesel weighs approximately 7.1 pounds per gallon.
There are on road and off road models of nitro RC trucks. Choose an off road model for dirt roads. More information is available at http://www.rccartalk.com/nitro-rc-cars.html
Trucks - 1999 Jeep Wrangler Off-Road Upgrades Part 1 was released on: USA: July 2011
Trucks - 1999 Jeep Wrangler Off-Road Upgrades Part 2 was released on: USA: October 2011
Toyota Racing Development
I know a Walker Evans who raced off-road trucks.
Michael Bargo has written: 'Off-road high-performance handbook' -- subject(s): Automobiles, Handbooks, manuals, Modification, Off-road operation, Off-road vehicles 'A facilitator's manual for Choices and decisions' -- subject(s): Values 'Chilton's off-roading guide' -- subject(s): Off-road vehicles 'Monster trucks' -- subject(s): Monster trucks
RC off road trucks should really not be used by anyone under the age of 5 as the car itself contains small parts etc that could potentially cause a hazard
The best place to look for RC off Road trucks in the D.C. area would be via websites such as amazon.com or by searching for the item on ebay.com. Both of these websites are large companies that stock a large variety of products.