Budget / Avis Rental Car Tires

We recently rented a 2018 Ford Explorer Limited from Budget / Avis. During our drive the rear stepped out (slid) on two occasions. We took a look at the tires and were a bit appalled.
The rear tires on both sides were down to the wear indicators. Basically no tread left. Keep in mind this is in the US Northeast during winter with ice and snow on the ground.
Holly picked the car up, did not check the tires. And I typically do not check the tires when I pick up the vehicle (I tend to take a closer look when I photograph the vehicle). This has never been an issue for us, but we will certainly be on the lookout in the future.
Following are some images of the tires taken with my phone:
Driver front:

Passenger front:

Driver rear:

Passenger rear:

 This one had some pretty bad damage...

 

In order to mitigate our risk while driving back from Burlington, VT to Boston, MA we went on both the Budget / Avis websites and searched for available vehicles in the Burlington, VT area. All locations were listed as sold out (it was a three day weekend).
We then called the support / roadside assistance phone number. They also searched both Burlington and Montpelier and could not find any available vehicles (or many open locations on a Saturday afternoon). So we drove back to Boston.

When we dropped the vehicle off at the Boston Logan International Airport rental car center we brought their attention to the tires.
The personnel told us to go in and speak to a manager behind the rental counter. The personnel behind the counter were also surprised that a vehicle with only 32,470 miles had tires in such terrible condition. They thought the tires should last longer. They said the vehicle will be removed from service. They stated that because of the volume of vehicles rented not every vehicle is inspected for tires and mechanical things between each rental.
They then told us that because we prepaid for the rental they could not do anything at this moment. That they did not have the manager they needed on duty, and gave us the business card of Avis Budget Group, Inc. Airport Manager to send him an email with our concerns and to see what can be done for us.

I sent an email and received an automatic response that he is out of town until 02/25/2019. So, I will be sending another email on that date.

I will update this with additional information I receive in the comments.