Steering wheel shimmies

I have a 2001 nissan altima,have fairly new tires,balanced& aligned but the steering wheel shimmies at speeds 20 and below usually when just coasting.

Have the tires inspected carefully. There may be a tread separation or some other problem with one of the tires.

It could be defective tire. It also could be a warped brake rotor, or wheel bearing

Could also be a bent wheel.