Noise when backing up

I have a 2008 RAV4 (34K). When backing up, slowly, I hear a constant noise. Sounds like we are driving on snow/ice. Like something is rubbing. I hope it’s not grinding from anything important. Any ideas?

Sometimes if you have drum brakes in the rear, it can sound like they are rubbing. Sometimes they are rubbing, and sometimes they aren’t. I would have the rear brakes inspected. It might be something to be ignored, but get it checked out.

Thanks for the response. I’m pretty sure this is rear disc brakes. But in a month or so I’ll hit 35K and take it in for oil change/tire rotation. I have a very honest mechanic and I’ll tell him about the noise.