That sounds like lateral imballance, or perhaps loose lug nuts.
Radial imbalance shows up at roughly 55 to 60 MPH. Lateral imbalance shows up at a much lower speed.
Most vibrations show up at a specific rpm (for that component, not necessarily engine speed), and it returns on multiples of that speed.
Lateral imbalance usually shows up about 25 to 30 MPH and repeats at double the speed.
Steering can be edgy with lateral imbalance because the sideways shake nibbles at the steering.
