Why did Mattie throw the five-gallon can at Taylor? Why did this remind Taylor of Mama?

Eventually, Taylor tells Mattie about her secret fear of exploding tires. Mattie takes a five-gallon can and fills it halfway with water, then throws it at Taylor. She tells her that it is twenty-eight pounds of water, which is the weight in a tire. She says that the damage Taylor just suffered (she just got the wind knocked out of her) is the worst that could happen with the small tires in the shop.

Taylor tells Mattie about her secret fear of exploding tires. Mattie takes a five-gallon can and fills it halfway with water, then throws it at Taylor. She tells her that it is twenty-eight pounds of water, which is the weight in a tire. She says that the damage Taylor just suffered (she just got the wind knocked out of her) is the worst that could happen with the small tires in the shop.