Well, what are you wearing in your ears now that are 36mm? You don't need to necessarily buy new plugs, though I'd recommend it, because 4mm is not small business. Either way, PTFE tape on your plugs means not buying new plugs to stretch, but using the tape to stretch. You can get a roll for about a buck in hardware stores.
Zman lo mechakeh, lo otser, lo nishar - Idan Raichel
(Time doesn't wait, doesn't stop, doesn't stay.)