An older movie about an American boy that goes to Africa with his family and befriends another little boy?

This movie is about 40 years old. The boys find an old truck tire and get in it and roll down a slope, but when the African boy gets in, the tire rolls off the slope and the boy gets a severe head injury. In the end, I think he goes to New York with the family to see a specialist about his head injury. I have tried to post this question 3 times, but it keeps getting deleted. All I did was mention the races of the two boys for description. This is not a racist question. I saw the movie when I was about 10 years old and it touched me deeply. Now 40 years later, I would like to watch it again. Thanks