So I have a 2008 CB400 that I love very much. No problems with it so far, never had anything wrong with the bike, no punctures, no cracks, no...nothing with the tyres, yet, for the past few weeks, whenever I go check my tyre pressure in the morning, it's dropped a fair few psi. Over a week, it used to go down 2-3 psi (which feels pretty normal) but in the past 2 weeks, it's started dropping 7-8, even 10, usually only on the rear, but sometimes on the front too. Friend suggested it might simply be someone sneaking around deflating my tyres, but I don't see why they would nor do I see when or how they'd do it, considering where I park every night. I've checked multiple times, and there are no cracks, no punctures, nothing stuck anywhere and there's no visible leaks coming from anywhere (spraying water all over the tyres, nothing shows up anyway). So, what gives? Anyone have any ideas? I've checked at home, with my own gauge, I've taken it to three different petrol stations to check, all with the same results. It's starting to get a bit frustrating. Oh, I've got a fairly new set of Pilot 4s (my second pair, as they've worked perfectly so far) and as I said, never had any issues in the past.