What caused the rumble in the outsiders?

Answer 1

The rumble in "The Outsiders" was caused by the ongoing rivalry between the Greasers and the Socs, two rival gangs in the novel. The tension between the two groups had been building up throughout the story, culminating in a physical confrontation to settle their differences. The rumble was a way for the Greasers and Socs to assert their dominance and prove their strength in their ongoing conflict.

Answer 2

Since i just Finished the book in my 8th grade class, I think i might have a idea. The Socs were getting to far into the Greasers territory and they kept getting more mad at each other so when Johnny killed a Soc both sides had enough. That's only what I think, it may be right and it might not only the author can give the perfect answer.