What kind of durability will your product demand? For example, there's a world of difference between pencil erasers and airplane tires, both commonly made from rubber. Be sure to choose manufacturer that can advise you on the ideal material for your performance needs, and that can provide rubber testing capabilities.
Funny you mention that...
I snatched up an airplane tire once and oddly enough... I suddenly felt the urge to erase things with it...
>
>
>
>
Too heavy... Tore the paper... and smudged...