[Motor31]

The best bet is to use a service like Stripits, where each wheel is weighed so you get side to side load info as well as axle / tire load info.

If that's not possible you can get it weighed at a truck stop scale. Just look to see if the scale is certified accurate and frankly if they are selling the service, state regs will require that they be certified and tested by the state's dept of weights and measure.

Make sure the tow vehicle has each axle on a seperate pad and that the trailer axles are on one pad. Then drop the trailer and weigh the truck separately. Subtract the unladen truck rear axle weight from the loaded rear axle reading and you will have your pin weight for the trailer. It's not as good a weight resource since you won't know if you are heavy on one side or the other or if any particular axle / tire is overloaded. You'll just get the gross weight of each and the combination.

Stripit's (Stacey) can give you the best weight "product" if you can meet up with him, or another who does the same thing.