## 2 Materials and Methods
### Mixing Procedure  
Mixing of the CB-filled compounds was performed using an internal mixer (Brabender Plasticorder 350s) with a mixer temperature initially set at 50 \({}^{\circ}\)C, and a rotor speed of 130 revolutions per minute (rpm). NR was initially masticated prior to the addition of BR. The masticated NR and BR were blended for 1 min (min). Then half of the CB and TDAE oil were added and mixed for 1 min. After 1 min, the other half of CB and TDAE oil were added and mixed for another 6 min. Finally, all other ingredients: ZnO, stearic acid, 6 PPD, and TMQ, were added and mixed for 2 min. The compounds were dumped, sheeted out on a two-roll mill, and kept overnight before incorporation of sulfur and CBS in the same internal mixer at a set temperature of 70 \({}^{\circ}\)C and initial rotor speed of 50 rpm. For this, the masterbatch was mixed for 1 min, the rotor speed was decreased to 30 rpm before curatives were added, and the compound was mixed for another 2 min. For CB/SI- and SI-filled compounds, the mixer temperature and rotor speed were set at 100 \({}^{\circ}\)C and 60 rpm. The masticated NR and BR were blended. In CB/SI, silica and \begin{table}
\begin{tabular}{c c c c} \hline  & \(\mathbf{\delta}\) **(MPa)\({}^{\text{(1)}}\)** & \(\mathbf{\delta}\) **(MPa)\({}^{\text{(1)}}\)** & 1 \(\mathbf{\delta}\) **(\({}^{\text{(1)}}\),NMR)\({}^{\text{(2)}}\)** & **(\({}^{\text{(1)}}\),NMR)\({}^{\text{(2)}}\)** \\ \hline Natural Rubber (NR) & 16–17 [15] & 17.8 [16] & – \\ \hline Butadiene Rubber (BR) & 16–17 [15] & 17.7 [16] & – \\ \hline NR/BR blends 70/30 & – & 17.7 [16] & – \\ \hline Terpene Phenol (TP) & 16–23 [16] & 20.2 [2] [16] & 2.4 \\ \hline Aromatic hydrocarbon C9 (C9) & 18 [17] & 19.4 [16] & 1.6 \\ \hline TDAE & – & 17.2 [14] & 0.5 \\ \hline \end{tabular} \({}^{\text{(1)}}\) Calculation of the Hildebrand parameter from group contributions of the molar vaporization energy (U) and molar volume (V) at 25 \({}^{\circ}\)C. \({}^{\text{(2)}}\) Two molecules of terpene and one molecule of phenol are assumed.  
\end{table} 
Table 4: Solubility parameters (\(\delta\)) of polymers and resins. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Ingredients** & **Carcass** & \multicolumn{2}{c}{**CB**} & \multicolumn{2}{c}{**CB/SI**} & \multicolumn{2}{c}{**SI**} \\ \cline{3-8}  & & **C** & **TP/C9** & **C** & **TP/C9** & **C** & **TP/C9** \\ \hline NR (RSSR1) & 100 & 70 & 70 & 70 & 70 & 70 & 70 \\ \hline BR (HC LCB BR) & 0 & 30 & 30 & 30 & 30 & 30 & 30 \\ \hline CB (N2S4) & 25 & 55 & 55 & 35 & 35 & 0 & 0 \\ \hline SI (ULTRASIL 7005) & 0 & 0 & 0 & 20 & 20 & 55 & 55 \\ \hline TESTP & 0 & 0 & 0 & 1.7 & 1.7 & 4.8 & 4.8 \\ \hline ZnO & 5 & 5 & 5 & 5 & 5 & 5 & 5 \\ \hline Stearic acid & 1 & 3 & 3 & 3 & 3 & 3 & 3 \\ \hline
6 PPD & 1 & 2 & 2 & 2 & 2 & 2 & 2 \\ \hline TMQ & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ \hline Resin & 0 & 0 & 7.5 & 0 & 7.5 & 0 & 7.5 \\ \hline TDAE & 4 & 7.5 & 0 & 0 & 0 & 0 & 0 \\ \hline Sulfur & 2.5 & 1.5 & 1.5 & 1.5 & 1.5 & 1.5 & 1.5 \\ \hline CBS & 0.7 & 1.5 & 1.5 & 1.5 & 1.5 & 2 & 2 \\ \hline DPG & 0 & 0 & 0 & 0.4 & 0.4 & 1.1 & 1.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Compound formulations: quantities are given in phr (parts per hundred rubber); molar ratios of NR/BR are given in Supplementary Materials, Table S5. silane were added first and mixed for 1 min. At the second addition, CB was added with other rubber ingredients except for curatives. In the SI-filled compounds, half silica and silane were added after mixing rubbers, and the other half of the silica-silane filler and remaining ingredients except curatives at the second addition. The rotor speed was then adjusted/decreased to reach the temperature for silanization of 150 \({}^{\circ}\)C. The temperature of silanization was maintained for 7 min and 9 min for the CB/SI- and the Si-filled compounds, respectively. After 3 min of silanization, the ram was opened for about 1 min to release ethanol generated in the silanization reaction. Then the compounds were discarded.