From military.com :
The Ohio Class submarine is fitted with four 533mm torpedo tubes with a mk118 digital torpedo fire control system. The torpedoes are the Gould mk48 ADCAP torpedoes.
...their torpedo rooms were made relatively small, with four tubes like the Los Angeles-class but room for only some 12 of the standard ADCAP Mark 48 torpedoes or Mark 30 torpedo-sized decoys. This made sense when the ship's mission, in an anti-submarine context, was purely defensive. But if an Ohio had launched all her Trident C-4 or D-5 missiles, she could then switch to the offensive, acting as an ersatz fast-attack SSN, hunting and engaging hostile SSNs and SSBNs.