Soft surface floors such as Carpet, require a hard wheel. 
Hard surface floors require a soft wheel.
(A mat over a carpeted floor is considered hard surface flooring, not carpet!)

What is the advantage of a larger wheel?
• Larger diameter wheels can roll easier and more freely over dirt, grit, flooring imperfections and small fallen objects.
• Larger wheels can add to the overall maximum height.
• Larger wheels support more weight.
• Larger wheels permit (much) easier "push off". Push off is when you push away from your desk while still seated

Abacus offers hard or soft wheel Barrel type non-Shepherd Castors shown with most all Gas or Manual Base styles. Especially designed to perfectly match the base leg tip contour. Available in 2" (50mm) Hard or Soft, or 2 3/8" (60mm).
Choose other replacement 2" to 3" or larger castors for existing swivel chairs and also for Base series #7201 & #7303 from our Shepherd brand castor selection.
Our Shepherd castors are Industrial quality. Industrial castors have all metal bodies which exceed rigorous BIFMA/ANSI testing standards. Although they may look identical to residential and plastic castors, they are made from different materials than what is commonly sold at Hardware stores, Do-it-yourself centers, and Office store suppliers.

For Home or Office,

On Wood and Ceramic Tile floors, a non-marking soft rubber wheel such as the Shepherd Saturn is recommended. The larger 3 1/2" is perfectly suited for bridging the grout depression on tiled flooring.
On Wood, Vinyl tile floors or Plastic mat, use either Shepherd Saturn or Pacer dual wheel Urethane castors.

For Carpet flooring, Regent hard Rubber, Baron or Pacer and Planet are the best choice.