Hello! So i know when i was searching for a wheel, i tried to find comparisons of all the sizes, and there wasn't really much, so i thought this would help out a bit for anyone in the future trying to compare the sizes
Red- 4.5 inch comfort wheel
Green- 6.5 inch Silent Spinner
Smaller Blue- 8.5 inch Comfort wheel
Big Blue- 12 inch Silent spinner
Hope this helps!