The bag contains only two covers, tires used for 1/8 cars, and on any car the hex size for the tire is 17. The tire type is s7GTV02-S7. Due to the nature of high speed racing, the Velocity tires do not have a replacement guarantee. Under controlled circumstances, Velocity tires have withstood speeds up to 160 Mph. The track surface can have negative effects unforeseen in our testing. The end user must realize that slight nicks can lead to tire failure at speeds that exceed 100 Mph.