We have all seen mattresses and furniture sitting on the side of the highway from overloaded and improperly secured cargo. That can be incredibly dangerous. It is very important not to overload your car or your truck when you move. It is extremely unsafe for you and others on the road, and your cargo can be damaged. In most places you will receive a ticket for driving an unsafe vehicle.
You can check your vehicle owner’s manual for maximum loading weight and tow capacity. If you are renting a truck or trailer you can find the specifications online to find out the necessary information. When in doubt you can always rent one size up or make multiple trips.