[denverpete]

It does sound like tires. There could be several reasons for this.

First, the tires are worn. If they are still the factory tires, I'd be surprised if they had much tread at 26K miles.

Second, the tires were rotated on the rear and are now facing the wrong direction since they are not made to be rotated. This means that you might have treads facing the wrong way and causing the humming.

Lastly, some tires get louder as they wear - even with quite a bit of tread left.