Aluminum hubs coated with silicone are mainly used when a high level of heat resistance is required (up to a maximum of 200°C).
The standard depth of the coating is about 15-20 mm. 
Silicone wheels are used on packaging machines for the pharmaceutical and food industries, etc.
They are also widely used on gilding machines for wooden picture frames.
White silicone is more resistant to the abrasion than the red one.