Fuente: WIPO "hemp" A tire sidewall rubber composition comprising, per 100 parts by weight of rubber (phr): 90–100 phr natural or synthetic polyisoprene rubber and 0–10 phr of a second diene elastomer; 20–60 phr silica having a CTAB surface area of 20–200 m²/g; a silane coupling agent in an amount providing a silane‑to‑silica weight ratio of 5–20%; and 0–5 phr carbon black. Optionally, 2–10 phr of plasticizer and a covering agent selected from triethoxy(octyl)silane, diethoxy(methyl)octylsilane, diphenylguanidine, or polyethylene glycol is included at 0.25–2% by weight of silica. When cured, the composition exhibits a loss factor (tan δ_max) <0.15 and a shear modulus G* at 10% strain of 1.0–1.8 MPa (23 °C, 10 Hz).