Why doesnt Dally want Johnny to turn himself in? Why does Johnny insist on confessing?

Dally seems angry as they drive back, and Johnny and Ponyboy think it's because he is annoyed they didn't turn themselves in earlier, if at all, to save him trouble. But he explains "in a pleading, high voice" that he just doesn't want Johnny to get hardened in jail. Ponyboy realizes how tenderly Dally feels for Johnny, and thinks about what Dally might have been like before he was toughened on the streets and in jail. Johnny does not want to be "on the run" anymore. He wants to tell the truth about what happened.