Flat tire sound while driving

Does this vehicle sit for any extended period? Also, have you recently hit a pot hole or curb with that tire?

I suspect this is one of two things. First it is a flat spot on that tire from sitting for extended periods of time. Normally it effects all 4 tires but there is a chance that this tire is just worse then the others.

The other possible causes of this issue is the tread as separated from the inner structure of the tire and when that contacts the road it is making noise.

Unfortunately the only repair for either of these if they are not going away is to replace the tire. You will have to have the tires balanced to figure this out. In fact they will have to be road forced balance so you may want to call ahead to a tire shop and make sure they can do that.

However, unless the tires are new already, you will want to replace the tire on the other side of the same axle. So if you are replacing the right rear, you want to do the other rear as well. However, I would put the brand new tires up front and the others on the rear.

Here are some guides that will help with changing a tire:

https://www.2carpros.com/articles/wheel-removal-and-re-installation

https://youtu.be/f6WJtx3yz7Q

You didn't note that this is an all wheel drive vehicle but if it is then you will need to replace all 4 at the same time or you will damage the transfer case.

Let me know if you have questions.