How is the rim tape around the area? Mabye the valve hole has a burr or sharp edge or the rim tape has a sharp edge there?
Try some bigger tubes.. http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=5840
@hippy started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
How is the rim tape around the area?
Mabye the valve hole has a burr or sharp edge or the rim tape has a sharp edge there?
Try some bigger tubes..
http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=5840