No the clock doesn't start with the green light. It starts when the tire uncovers the beam. When I said the clock starts at the same time I meant if both cars have identical ET. The ET clock starts when the beam is no longer blocked. The reaction time is the time measured between when the green light comes on and you uncover the beam. .000 R/T means you uncovered the beam at exactly the same time the green light came on. Frustrations explanation is correct. The only difference between a .400 and a .500 tree is the time between the last (or only) yellow light and the green light exactly .100 It will take the driver .*** amount of time and the car .*** amount of time to react to either tree. If you're hitting .000 on a .500 tree you will be .100 on a .400 tree all else being equal. Since you can't speed yourself up , you need the car to uncover the beam .100 quicker on a .400 tree.
Doug
Doug