All good info in here. A couple of points though.

Actually you are supposed to have 8% of the total trailer weight on the tounge of the trailer.

Also the weight is not nessessarily the same as the weight on the front wheel. Sometimes those trailer wheels can be set back from the tounge a good distance which would be different from the tounge weight.

So if your trailer weighs 1000lbs you need 80lbs on the actual tounge of the trailer.

Mike Hill