I hadn't heard anything more about the Megabus crash(es) until I had a conversation with my father. A quick google search lead me to this Chicago Tribune article by by Jon Hilkevitch from the 17th.

The buses in both incidents were heavily loaded and operating on extremely hot days, two key factors that cause stress on tires, authorities said.

Okay...

A tire on a motorcoach loaded beyond its weight rating and operated at highway speeds for a significant period of time is more likely to overheat and fail, potentially placing the safety of passengers and other motorists at risk, the motor carrier agency said in a statement.

No shit, what'd you think the weight rating was for?

The weight limit for double-deck buses is 80,000 pounds, which is the same limit as for other interstate passenger buses, according to the motor carrier agency.

That's a lot of pounds...

But the three-axle configuration on Megabus vehicles allows a lower gross vehicle weight, between 53,000 and 61,000 pounds, officials said.

Oh, so Megabus skimped on it to make it cheaper and in the process cost people their lives. Fucking brilliant.

A fully loaded double-deck motorcoach could exceed the weight limit or the tire weight ratings according to officials... 

Well, sure it could if their dumbasses overload it.

...who declined to provide the weight of the accident bus near Litchfield.

Unbelievable. People don't disclose things when its bad for other people to find out. I've had my terrible customer service encounters with Megabus back in college; their complete and utter incompetence in that realm should've led me to the conclusion the whole operation is just as bad.