16/24= .666
So you will have to apply 33% more effort to turn the wheel
16/20 = .8
So 20% more effort
20/24 = .83
So 17% more effort.
I can palm steer my 67 Dart (273, 215/70R14 tires) in a parking lot (but just barely) most of the time it is hand over hand.
At over parking lot speeds there is no issue