There’s no reality of danger with Rottweiler dogs if they’re raised properly. They’re not indiscriminately aggress, and a properly raised and well-bred Rottweiler should never be aggressive with their owners, or anyone they see in a situation that is non-threatening, really. If you have a Rottweiler that snaps at your or growls at your other family members, then you might need to get it some professional help so that you can reshape the dog’s behavior. Talk to your dog trainer or veterinarian or a dog behavior specialist.
However, there are numerous times when Rottweiler owners will mistake the breed’s prerogative to grumble or talk as growling, but they’re totally different things. If your dog acts like it’s making rumbling sounds in the deep part of its throat, as you are petting him, or when he’s being loved on and relaxed, then he’s probably just expressing his contentment. It kind of like a cat purring, which is not an aggressive action at all, really.
Not all Rottweilers do this, but a lot of them do this, and real sound itself can change from dog to dog. Some will purr in a rumbling, low way, others will groan or grunt, and it’s a kind of individual thing. If it’s your initial Rottweiler, you could be confused by what is going on here, but if you look at his body language, you can usually tell the difference between real growling and “talking” as you begin to know him better. If puts his ears back or his hackles rise, stiffens his body, or curls his lips, then he’s not purring at all, and you might need to use caution or get some professional help or official input as to why he is behaving this way.