If you cannot see through the vehicle ahead of you, your following distance should be a minimum of:

An expanded cushion of space is needed if your motorcycle will take longer than normal to stop. If the pavement is slippery, if you are traveling faster than 40 mph, if you cannot see through the vehicle ahead of you, or if traffic is heavy and another driver may try to squeeze in front of you, open up to a following distance of five seconds or more.