Ahh semantics! My bet is Tyre and rim association do list cap as primary seal. Which as per them may be "correct" But I've never unscrewed a cap and had pressure behind it so that valve behind it has done a first class job. But this thread has deviated. It was about cost/value at large auto part stores. I recently needed some automotive electrical connectors nothing complex. Local large auto store price - 3 times what I could buy same style connector from Jaycar.
Bookmarks