Most of the guidelines for fork arm wear and tear relate to the thickness as the heal or, if it is related to alignment, then it is 30mm per 1000mm (or 3%).
Follow links below for advice from UKMHA and HSE:
Inspection and Repair of Fork Arms – PDF
http://www.hse.gov.uk/workplacetransport/lift-trucks/repairs.htm
Regarding damage or bending at the fork tip, there is not so much information available however, HSE suggest that, if damage is present then only the fork manufacturer is qualified to advise upon, and indeed conduct, any repairs. Their advice would be, if you are in any doubt, to either obtain advice from the fork manufacturer or replace it / them.