Here is what Brett Gorvy writes about Lars and his collection on the christies.com site

Taste Lines - The Five Important Paintings from the Collection of Lars Ulrich
Despite being the founding member, songwriter and drummer of one of the most famous hard rock bands in the world, Lars Ulrich does not fit the mould of the cliched rock star. On stage with his band Metallica, he may give the impression of a wild personality, but in private, Lars shows a great sensitivity and seriousness of spirit, sharp intelligence and deep passion. This is best reflected in his exceptional collection. Over the last decade, with amazing focus, scholarly research, and a good knowledge of the market, he has actively gone out to collect some of the true masterpieces of late 20th century painting.

I first met Lars in the summer of 1995 in London. Knowing of Metallica's bad-boy reputation, I must admit that I too was expecting a heavy metal hard-man. Instead I encountered a modest and astute individual in his early thirties and we soon became close friends. Since then, we have worked together to assemble a collection that follows Lars' taste for highly expressive, deeply emotive paintings.

Now based in San Francisco, Lars was born in Denmark, the son of tennis champion Torben Ulrich. His Danish roots drew him especially to the paintings of the CoBrA artists, an international group of painters working in Copenhagen, Brussels and Amsterdam in the early 1950s, who championed a primitive and highly expressionist art. Through careful study and bold acquisition, Lars concentrated on building an amazing group of works by the leading members of the movement, Asger Jorn and Karel Appel.

Lars' collection follows a taste line, which encompasses paintings that display dramatic expression, strong color and gesture, and work often informed by a deeper philosophical soul. His enormous Untitled painting by Sam Francis symbolizes for me, the journey of Lars as a collector, where swirling lines and splatters of bright paint create a Pollock-like frieze. Out of the chaos emerge a pattern and a clear linear direction.

It was Lars' desire to follow his taste line and to find a more contemporary exponent who painted with the same bold expression and primitivism as the CoBrA artists. He found him in the guise of Jean-Michel Basquiat. The latter was a modern day primitive, a street-wise graffiti artist, who reached superstar status in the 1980s, and whose short but brilliant spasm of a career ended with an heroin overdose in 1988. Lars was able to acquire several of Basquiat's finest paintings, but nothing compares to the staggering bravado of Profit I. This is Basquiat's Guernica. Here the artist creates an icon for Black America: his hero is both warrior and crucified victim, a self-portrait, shown emerging triumphant from the immense darkness. Basquiat fills the space with a graffiti of strange mathematical notations and symbols, as if he were trying to compute the vastness of this hell like a deranged Leonardo.

Above you can see one of the paitings for sale, "Women, Children, Animals" by Karel Appel. You can see all the art Lars have up for sale here