How often do you need to add air to Beringer tires?

I like the concept of the tubeless Beringer wheels, but I'm wondering how well they hold air. For those who are using them on either the mains or nosegear, how often do you need to add air?

Thanks,

Very happy with the Berringer nose wheel that has been on my 6A for about a year. Seems to hold inflation better than the tubed mains. Top up every 3 months is probably sufficient.