A process for producing polyethylene polymers including contacting ethylene and at least one C3 to C8 alpha-olefin comonomer with a polymerization catalyst on a particulate support in a fluidized bed polymerization reactor under conditions effective to polymerize at least part of the ethylene and comonomer and produce the polyethylene polymers, wherein the support has a d10 particle size as measured by laser diffraction of at least 18 microns, is provided.