| Abbreviation | Definition |
|---|---|
| SHR | Second Hendrick Racing |
| SHR | Stewart Haas Racing |
| SHTR | Shawnda Hibbeler TEAM Racing |
| SIDRA | Southwestern Idaho Desert Racing Association |
| SIR | Sport Injected Race |
| SIRA | Southern Indiana Racing Association |
| SJG | Stephen J Gerace |
| SJR | See Jane Race Trimaran Club |
| SKR | Saskatoon Kart Racers |
| SKR | Shin Kai Racing |
| SLR | Sport Light Racing |
| SLR | Super Low Racer |
| SMR | Super Mile Race |
| SMRA | Southeast Mud Racing Association |
| SMRS | Southern Midget Racing Series |
| SMRT | Southern Marlins Racing Team |
| SOAR | Southern Ontario Amazing Race |
| SOAR | Stay Out of Areas of Racing |
| SORC | Southern Ocean Racing Conference |
| SORC | Southern Offshore Racing Committee |