Hearing a howling sound coming from rear axle?

Hello,

If the howling noise started as soon as you have the tires installed then the noise likely due to the tires.
Besides the tires the most common reason is the wheel bearing for the rear. The bearings can go bad and make howling noise. It usually goes down as you slow down and the bearing will have to spin less.

Here is a helpful article on howling noise:

https://www.2carpros.com/articles/car-howling-noise

I have attached diagrams for your reference.

Please let me know of any questions.
Thank you.