Row as hard as possible for 1 minute and then immediately go into tire flips for max reps in 1 minute. Your score is calories plus flips. Rest 4 minutes and repeat x 5 rounds. Hard for me to set an Rx weight for the flips but men should be around 600 and women around 350. If you get 20 flips in the first round the tire is too light. If you get 2 flips then the tire is too heavy.