What are pizza wheels in sublimation printing

So this is our 1 st post in a series of dealing with Pizza Wheel marks in sublimation printing 

Pizza wheels are small dotted lines which can appear after printing, after pressing or both and are caused by the paper feed rollers at the front inside the printer 

This is a typical plastic feed roller

they are always located at the front and inside the printer - You also have metal feed rollers inside but generally speaking these don't cause any issues

The plastic feed rollers should not be be confused with ones that maybe seen outside when standing in front of the printer like below

Things that can attribute to these wheels marks and how you solve them are 

1 Printer settings - 

2 Image type and density 

3 Moisture

4 Paper type vs steps 1-3 above