Golf ball with large inner core

A golf ball comprising an inner core, an outer core, an inner cover, and an outer cover wherein the inner core is encased by an outer core wherein the inner core has a volume greater than the outer core, inner cover, or outer cover, the inner core and outer core are substantially free of fillers, and the inner core is comprised of polybutadiene, a crosslinker, a co-crosslinker and an organo-sulfur compound, and the outer core is comprised of a highly neutralized ethylene copolymer,

• wherein the inner core has a specific gravity ρ12, the outer core has a specific gravity ρ14, the inner cover has a specific gravity ρ16, and the outer cover has a specific gravity ρ18, wherein the relationship between the specific gravities is expressed by the mathematical expression:
• ρ16≧ρ18≧ρ14≧ρ12.