, ▁reduce ▁energy ▁efficiency ▁and ▁may ▁even ▁cause ▁a ▁der ail ment . ▁A ▁rail road ▁wheel ▁typically ▁consists ▁of ▁two ▁main ▁parts : ▁the ▁wheel ▁itself , ▁and ▁the ▁t ire ▁( or ▁ty re ▁in ▁British ▁English ) ▁around ▁the ▁outside . ▁A ▁rail ▁t ire ▁is ▁usually ▁made ▁from ▁steel , ▁and ▁is ▁typically ▁he ated ▁and ▁pushed ▁onto ▁the ▁wheel , ▁where ▁it ▁remains ▁firm ly ▁as ▁it ▁shr inks ▁and ▁co ols . ▁Mon ob loc ▁whe els ▁do ▁not ▁have ▁enc ir cling ▁t ires , ▁while ▁res il ient ▁rail ▁whe els ▁have ▁a ▁res il ient ▁material , ▁such ▁as ▁rub ber , ▁between ▁the ▁wheel ▁and ▁t ire . ▁ ▁W heel ▁geometry ▁and ▁fl ange ▁ ▁Most ▁train ▁whe els ▁have ▁a ▁con ical ▁geometry , ▁which ▁is ▁the ▁primary ▁means ▁of ▁keeping ▁the ▁train ' s ▁motion ▁aligned ▁with ▁the ▁track . ▁Train ▁whe els ▁have ▁a ▁fl ange ▁on ▁one ▁side ▁to ▁keep ▁the ▁whe els , ▁and ▁hence ▁the ▁train , ▁running ▁on ▁the ▁rails ▁when ▁the ▁limits ▁of ▁the ▁geometry - based ▁alignment ▁are ▁reached , ▁e . g . ▁due ▁to ▁some ▁emer gency ▁or ▁defect . ▁See ▁Hun ting ▁oscill ation . ▁Some ▁whe els ▁have ▁a ▁cyl ind rical ▁geometry , ▁where ▁fl anges ▁are ▁essential ▁to ▁keep ▁the ▁train ▁on ▁the ▁rail ▁track . ▁ ▁W heel ▁arrangement ▁ ▁Whe els ▁for ▁road - ra il ▁vehicles ▁ ▁Whe els ▁used ▁for ▁road - ra