okgc wrote:
U-Haul shows this for their tow dolly rentals
U-Haul website wrote:
The vehicle-in-tow MUST be loaded facing forward (front wheels on tow dolly). Failure to load facing forward may result in sway or whipping and lead to total loss of control.
That's great as a general rule-of-thumb, and it's also a way for U-Haul to reduce their liability. But it's not a law, and there are definitely cars out there that can be safely towed backward on a dolly. I've seen many on the road that were backward and tracking straight & true, not swinging wildly.
Every car has different suspenion geometry (camber, caster, etc...), different weight distribution, and all of that will affect whether it can be towed backward or not. There is no one-size-fits-all answer.
The OP stated that his Miata tows very well backward, so it may be one of those that doesn't fit the general rule. And I've yet to see a law that forbids it.