Shinko Raven or Verge. They have bigger grooves and deeper tread than other tires, I ride on gravel frequently and these do very nice for street tires. And I have drug foot pegs, they simply work. And inexpensive.
There have been a LOT of substandard valve stems out there. On some the rubber will be bad in less than a year, as it was inferior grade.
On my 2 year old riding mower, I heard a pop while mowing, the metal part just shot out. Instant flat. All the valve stems were were very bad. Same size as used on motorcycles.
Always check your valve stems.