This invention relates to a pneumatic tire having a built-in non-black
colored sealant layer and its preparation. The sealant layer is derived
from a sealant precursor layer comprised of a butyl rubber,
organoperoxide, particulate, synthetic amorphous silica and plant-derived
organic agricultural seed flour, together with a non-black colored
colorant. The butyl rubber-based sealant precursor layer is build into
the tire to form a tire assembly and the butyl rubber component of the
sealant precursor layer is depolymerized during a subsequent curing of
the tire at an elevated temperature in a suitable mold to form the tire
having the resultant built-in sealant. The particulate plant derived
organic agricultural seed flour is a renewable raw material in a sense
that it can be replenished in nature and therefore not as a significant
depletion of non-renewable natural resource. The agricultural plant seed
flour is comprised of at least a portion of a ground plant seed (e.g.
whole or partial seed portion including for example its nucleus and/or
shell) of an agricultural seed producing plant such as, for example,
wheat, rye, rice, barley, oat, mullet, soybean and/or corn. The sealant
layer may also contain one or more of a liquid polyisoprene and short
organic fibers. Preferably, the amorphous silica is a precipitated
silica, namely aggregates of primary silica particles.