Sfera 63mm Figure Wheels

Sfera wheels are modeled after Star wheels which were considered as a top-tier roller skating wheel for figures, praised for their exceptional smoothness, good grip, and high quality materials.  Five (5) hardness options are available to adapt to various skating surfaces with varying amounts of grip.
 
The lower the Shore “D Scale” rating, the softer the wheel, the more the grip, less roll.
The higher the Shore “D Scale” rating, the harder the wheel, the less the grip, more roll.
SFERA has a profile of 32mm and is original Star compound.
Both the Roll-Line Giotto and new SFERA are 63mm in diameter.
 
The tread color identifies which hardness the wheels are.
Blue = 47D – Least Grip / Slippery
Grey = 49D – Slightly More Grip
Cream = 53D – Medium Grip
Yellow = 57D – Adherent Surfaces
White = 60D – Very Adherent Surfaces
 
Set of 8 wheels
 
In the USA, most skaters use the 60D, while stepping down to the 53D or sometimes the 57D for the inside toe wheels as additional push wheels.
The softer the wheel, or lower shore “D” hardness number, the more the grip and slightly less roll. The harder the wheel, or higher shore “D” number, the more the roll, with slightly less grip.  The shore “D” scale is used for rubber and plastics, while the shore “A” scale is used for urethane.
 
It is almost always recommended to use spacers in the wheels, when using standard 7mm bearings.