this time next week the TIRN's convert to normal TIR's, therefore anyone with TIR's should be selling them and buying an equal amount of TIRN's for 10% cheaper. Also get the funds for your TIR's on the 10th and not have to pay for your TIRN's until the 18th.
Maybe there is a free lunch?
Check it out with your broker, don't take my word for it.