Original: Soundgarden supported Ultramega OK with a tour in the United States in the spring of 1989 and a tour in Europe, which began in May 1989 and was the band's first overseas tour.
Simplified: Soundgarden supported Ultramega OK with a tour of the United States in the spring of 1989 and a tour of Europe which began in May 1989 and which was the band's first overseas tour.