Odometer check
A short, measured section at the start of a TSD rally where the crew compares its odometer with the official distance (also odometer calibration run, OCR).
The odometer check (also odometer calibration run/zone) is a short, officially measured section – usually about 10 miles – at the start of an American TSD rally. The crew drives it and compares its own odometer reading with the rallymaster's official distance. This gives the correction factor ('theirs over ours'), used to convert all the distances in the route instructions to the crew's own odometer. It thus compensates for odometer measuring error. It corresponds to the European reference section or 'measured mile'.
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Related terms
Regularity rally
Classic-car motorsport where precision counts, not speed: hold prescribed average speeds and target times as exactly as possible.
Distance
Precisely measured length of a route section – the basis for calculating target times and average speeds.
Correction factor
The factor from the odometer check used to convert the rallymaster's distances to the crew's own odometer – calculated as 'official distance divided by your own'.