Q: Are trailers titled?
In the state of Ohio, trailers are titled if they weigh 4,000 lbs or more. If they weigh less than 4k lbs, they will have a certificate of origin. A certificate of origin is similar to a title but it doesn't have a title fee or get ran through the states title bureau. It is a legal document that has information like the VIN, weight, manufacture date, and GVWR. It is important to hold on to.
Other states may vary but you can "flip" the certificate of origin into a title if your state has different laws on titles.
Q: Do I need to insure my trailer?
The laws vary from state to state. In Ohio you do not. It is a good idea to add your trailer on to your vehicle policy or business insurance. Most insurance policies are very affordable when it comes to adding a rider for trailers.
Q: What does GVWR (gross vehicle weight rating) mean?
In simplest terms, GVWR is the max loaded weight of the trailer and cargo. If your trailer is rated for 7,000 lbs then that means the manufacturer has rated it to weigh that amount loaded. Weight of the trailer + cargo = gvwr. If a trailer weighs 3500 lbs empty and it is rated for 7,000 lbs then it can carry 3500 lbs.
Q: What determines the GVWR of a trailer?
GVWR (gross vehicle weight rating) is set by the manufacturer of the trailer and towing vehicle. Typically that is determined by the frame and axles. The axles of a trailer are the main factor of the weight capacity. Single axle trailers without brakes are capped at 2990 GVWR so they do not require inspection.
I am not a lawyer, LEO or representative of DOT. Please do your own research for your state / country because the laws may differ.