Nylon 6 having viscosity number within a range of 170-340 in a measurement
of a 98% concentrated sulfuric acid solution at 25.degree. C. and a
plasticizer are mixed in advance, and then the mixture is mixed with Nylon
66 having viscosity number within a range of 240-370 in the measurement,
thus a resin composite is prepared. Then, the resin composite is formed
into a tube by extrusion molding. The resin tube thus obtained is used as
a resin tube for automotive piping, such as vapor fuel piping to be
incorporated into a fuel tank or as oil piping to be incorporated into an
engine room.
