Originally Posted by Mjgman
Is it the total weight of the vehicle or just the front axle weight when using a tow dolly?
Both, and neither.
The tongue weight is next to nothing because the vehicle's front wheels are directly between the tow dolly wheels, and only the actual weight of the dolly's tongue is applied to the receiver. The car's front axle weight is applied to the dolly's axle weight, not the tongue weight.
But for horizontal pull, the entire weight of the towed vehicle, plus
the weight of the tow dolly, is applied to the hitch.
So in the case of an Interstate EXT, for example, with a towing capacity of 500lb. tongue weight and 5000 pounds gross trailer weight rating, one wouldn't come anywhere near the 500 pounds tongue weight, but could very easily exceed the 5000 pounds GTWR if the towed car has a GVRW close to 5000 pounds and the weight of the tow dolly puts it over.
If there's any doubt, weigh the towed vehicle before putting it on the dolly and go by actual weight rather than gross weight rating.