The type of 18th scale racing is indoor on carpet with off road style jumps.
Classes off the top of my head for club racing:
1. 18t, 18mt, m18t truggy
2. 10th scale st with foams
3. Buggy class - 18b, m18b, detta
4. Monster truck - vendetta st, mlst etc
5. Rally Class - 18r's
You can run foams or rubber tires for the 1/18th scale.