Bike is a K1 B12. The manual says to check the valve clearences on my B12 every 7500 miles. On other equally low-tech bikes In the past I've always left the clearences a bit without problems. (Usually doing them after about double the recommended milage). Is every 15k likely to be often enough on the B12? (It doesn't matter much - easy do do which is one of the reasons I've bought the bike.) Being lock nut adjustment will they tend to do wider, rather than narrower? (thus 'failing safe'?) Also It's on it's OE tyres and I'm not far off needing new tyres. Unsurprisingly, I want bucket loads of wear and loads of grip. What choices are there and which is best? (I'd be prepared to compromise a _bit_ on grip in wet etc in exchange for longer tyre life.)