Private charter bus companies that are contracted to run tours are notorious for ignoring equipment safety as it "costs too much" and money is the bottom line as they're in business to make a profit.
After I retired, I worked for a very short time driving charters and tours on a part-time basis --usually 40'+ MCI, Prevost, or Van Hool coaches-- and each time I brought up equipment safety concerns, I was told they'd get on it but seldom did. This especially had to do with TIRES! I quit soon after. I reported several of them to the state and federal agencies and I know one of them was forced out of business but there are still lots of them out there that for the most part disregard safety or it's very low on their agenda.
It was eye-opening for me as I retired as a transit bus operator and public transit agencies are typically (most of the time but not always) on top of equipment safety so much more
than private bus companies.
Public transit agencies are for the most part tax-payer funded and are not focused on making a profit as opposed to private charter bus companies where all they care about is MONEY.
I used to keep track of charter bus fatalities due to tires but I can't find my detail journal as I haven't done so for the past several years.
Here's a few, however, that happened after I quit driving charters in 2008 and I'm sure there were dozens more since then both with fatalities and not:
Bus in fatal crash had unsafe tread on tires, investigators say
Failed tire called cause of fatal Texas bus wreck
Tire failure named the cause of fatal football team bus crash
Bus Roadway Departure and Rollover