Can't find correct tube for 120/90-16 tire

I'm about ready to replace the rear tire and tube on my 82 KZ305. 120/90-16.
From my research, tube size should be 4.75. But the tubes I am finding are either 4.25-4.50-16 or 5.00-5.10-16.
Is it better to go with a slightly larger or a slightly smaller inner tube?
I could go to a 130/90-16 rear tire, as there are plenty of tubes for that size, But would rather stick to stock size.

Go with the smaller size. Less chance of pinching the tube.
Steve

This seams to validate Swest’s recommendation for size. Please confirm stem type you need.

www.americanmototire.com/motorcycle-tube...0-16-120-90-16-tr-4/

Found this chart to correctly size a tube to a tire.

www.cb450stuff.com/tire-size-conversion.html