Nacho Cheese

I think he was going to the shoulder to avoid hitting the semi in the right lane, not necessarily pass. You can see he braked way too late to avoid the car and semi. If he was paying attention he would've saw why they were going slow and knew there would be a truck on the shoulder.

Even if we assume his story is true and his passenger steer tire blew, it still doesn't explain why he waited until he was on the car's bumper to start braking.