Most theme parks have height requirements for some of the rides. Disneyland in California is no exception. Keep in mind that the rules are there for a reason, Disney is concerned about the safety of the smaller guests. If you want to ride but your child is not tall enough ask a cast member for a Rider Switch Pass. If you don't know whether or not your child is tall enough to ride he or she can be measured at the entrance to the ride.
At Disney California Adventure guests must be at least 32 inches tall and accompanied by another guest who is 54 inches or taller in order to ride Luigi's Flying Tires and Mater's Junkyard Jamboree. Only guests 36 inches or taller can ride Tuck and Roll's Drive'Em Buggies. There are five rides where you must be at least 40 inches to ride; The Twilight Zone Tower of Terror, Jumpin' Jellyfish, Soarin' Over California, Radiator Springs and the tandem swings on Silly Symphony Swings. Guests must be 42 inches or taller to enjoy Grizzly River Run or the zip line and the rock wall at Redwood Creek Challenge Trail. Finally, there is a 48 inch height requirement for the single Silly Symphony Swings and California Screamin'.