I think Pirelli and Ecclestone-side do differ on how they are fundamentally interpreting existing tire contract and its extension for 2014. (I haven't seen it, but could be some mundane clause which was misinterpreted; for example, you have to give notice to the contractual party that you wish to withdraw your services by certain date, and Pirelli might have failed that, thus they are "stuck", or something similar). There were some interviews published a few months back which sounded to me as being centered on differences and over how the existing contract is being interpreted.
Edited by Sakae, 21 June 2013 - 14:46.