First, a 7.00-10 is an old tire sizing system I can't find any modern equivalent, so that means we need to start from scratch.
So what are you going to use the trailer for? If it's to be towed on the street at highway speeds, then we need to be careful. Many 10" tires are designed for slow moving vehicles.
Second, is there loading information on the tires anywhere? That will give us a clue as to where to look. Consider you might have to buy both tires and wheels - maybe even in a different wheel diameter.
So help us help you. Describe what you are going to use the trailer for. What more information is on the tires. Are the wheels marked with a size? (Might need to dismount the wheel, because the size might be on the back.)