how do you determine the roll out on your car ?

[stracer859]

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[CoMax Racing]

The roll out of your car is the distance you travel when your tire first breaks the stage beam to when it leaves it. (Light bulb turns on to when the light bulb goes off again.) Taller tires therefore will have more roll-out giving you that much more advantage, and they also lessen the chances of red lights in some situations.

[Flyby]

The most accurate way I've found is to go to your local track. At some tracks the rollout is different because the light beams light sources are different or they are set at differing heights or distances. When there is a rain delay ask them if its ok to measure your rollout. They won't mind as long as you don't go down the track. You could use a bicycle tire thats the same size with tape at the bottom of the spokes but it's more accurate with your car, at racing weight with the air pressure set.

Bring the car to the line and shut it down, slowly roll the front tire in by hand through the prestage light until the staged light just flickers on. Tape a string with a plumb bob or a pointer on to the body or rocker panel with the point 1/2 inch above the ground. Put a tape measure under the plumb bob and move the tape to an even number like 1 foot. Roll the tire forward until the rear edge of the front tire passes the beam and shuts off the lights. Look down at your measurement on the tape and count the inches you have moved. Thats your rollout. The air pressure in your tire will change that number so make sure you set it first.