Is not a good idea to lose either rubber. The sprocket does not need to be tight agenst the hub. It just has to be perfectly centered. On many of the less expensive bikes, the sprocket dosent even come close but if well centered is no problem. BE has a great how to install the sprocket section. 4-Stroke Engine Kit Installation
(The rag joint is the same for both the 2 and 4 stroke)
Below are some pics of a Point Beach set up. The sprocket it self touches none of the wheel.
Hope that helps and was your concern.