Check whether the JJRC C8815 RC car steering tie rod is loose from the helm and wheel connection parts, and tighten the loose screws. Check if the wheel bearings are worn, and replace the bearings if they are worn. In addition, lack of oil or damage to the steering ball head can also cause rattling, add lubricant or replace the ball head. Check if there is any foreign matter embedded in the tire tread, clean up the foreign matter and then test if the steering still rattles.
Also, if the wheels are too big, it could be caused by cutting into the car shell.