Managers Asking About Incompetent Co Worker

Hi,

I've been working at this company for a year now and I have a very, very bad co worker, let's call him Bob, who should've been fired a long time ago, but due to corporate structure (our main office and managers are across country), a lack of accountability, an organizational split where our old boss was going to fire him but dumped him onto someone else, and me picking up his slack, he's managed to survive for the past year.

Bob has been a junior engineering for over 10 years when he should probably be a technician. He is the least technical member of our group, and actively avoids work, which means I've been doing a lot of his job for him for the past year. I'm convinced if it weren't for me, he finally might have gotten noticed and fired. From November to Feb of this past year, he had a habit of coming in two hours late and only two days a week (he would "work" from home), which he got away with because we didn't have any supervision. Bob and I work in operations and often times we are the only ones on shift. However, Bob let's me do all the work by actively ignoring requests or doing a piss poor job addressing alerts. Often times he leaves the room when shit breaks and it's something he doesn't know how to handle, which leaves me with the bulk of the work while he watches youtube for 5-6 hours during his 8 hour shift. I've never actively confronted Bob on his work ethic or behaviors, but I've encouraged him to be more pro-active and to investigate issues deeper before writing them off. I've also done my best to answer any questions he has had and have never withheld any knowledge or information from him regarding our job. I know people exaggerate when talking about bad co-workers, but I'm not exaggerating here.

Bob and I also don't get along. I think he's a shitty person and quite frankly, a bitch. He probably thinks I'm a hard ass who takes my job too seriously.

I was fine ignoring him, picking up his slack when needed, and never complained to management about him because I wanted to be bigger person and sometimes complaining does you no good. Having said that, in the past two months, our manager has asked me questions about him, and the VP of our department has started asking me questions about him and his work ethic. I didn't really let on what was going on, but mentioned we might need more leadership in our office, and when our VP, who is the kind of guy who has zero tolerance for bullshit, asked me questions about him, I did my best to say good things about him because as much as I hate him and don't like working with him, I don't want to jeopardize another man's livelihood.

Should I tell my managers the truth?