A good wheel must have the following characteristics:1. Plastic wheels are strong but not hard, so they don't pull up quietly and the noise won't be too loud. Otherwise, if you walk in the airport hall or the railway station, other passengers will think that there are tanks coming in. Looking back, it's a broken box, and you will be laughed at generously.2. Wheels must have bearings, bearings will be durable and will not grind wheels, and bearings will be more flexible and easy to control. hashtag3. Wheels should not be too hard or too soft, just like car tires inflated, tugbox wheels are too hard to pull, too loud and easy to crack into dead wheels, too soft to pull too hard.