National number rules from SCCA National Solo Rules 3.7 VEHICLE IDENTIFICATION
- All vehicles must display numbers and class letters on both sides, which must be readable by Timing & Scoring, Course, and Grid workers at all times.
- Only one set of numbers and class letters may be visible while the vehicle is running.
- Class shall be represented by the upper-case abbreviated form rather than be spelled out. (Example: “BSP” instead of “B Street Prepared”).
- Numbers and class letters should be positioned next to each other. All letters and numbers must be on body panels, not on windows. All numbers and class letters must use the same typeface and the same color, and this color must provide adequate contrast to the background color.
- Numbers must be a minimum of 8" high with a 1.25" stroke. Class letters must be a minimum of 4" high with a 0.75" stroke. In all cases, the height of the class letters must be between 25% and 75% of the height of the numbers. Stroke width must be at least 10% of the height.
- The “1” on two-driver cars is subject to all of the above requirements with regard to placement, color, size, and stroke.
- Karts may use numbers and class letters of reduced size provided that the following conditions are met:
- Numbers must be displayed on the front and rear in addition to both sides;
- Class letters must be on both sides;
- In no case may the numbers be smaller than 6" in height with ¾” stroke, using a high-contrast color and background.
- For National Championship, National Tour, and Divisional competition, current official SCCA required decals must be displayed on each side of the vehicle in a prominent location. For Divisional, Tour, and National Championship events, one official SCCA approved National sponsor identification logo must be displayed in an upright position, in a prominent location on each side of the vehicle.
Additional local rules:
- There must only be one class designation on each side of the car. Cars running indexed classes (X, W, AT) must have only their index class designation on the car (X, not SSX; AT, not SSAT; W, not SSW)
- Car numbers will be reserved on a first come, first-serve basis. Only one or two-digit numbers will be allowed (i.e. 0 through 99). Exception: Where there will be two drivers using one car, then the second driver will use 100 plus the first driver's number. (e.g. 30 and 130, 99 and 199)
The following illustrations are intended as examples to help guide competitors in the placement and sizing of their numbers and class letters.