We derive analytical expressions for the growth factor, D(z), and density-weighted growth rate, fσ8(z), for cosmologies in which a ∝ t at late times. We fit fσ8(z) to data from redshift-space distortion measurements in the redshift range z < 2 using the dynesty implementation of nested sampling. Three coasting models, with curvature parameters k = {−1, 0, +1} in H2 0 c −2 units, and a flat ΛCDM model are tested. We evaluate each model’s consistency with the data by applying the Anderson–Darling test for normality on the normalized residuals. We obtained Ωm,0 = {0.206+0.073 −0.061, 0.297+0.085 −0.073, 0.412+0.097 −0.086} and σ8(z = 0) = {1.071+0.213 −0.151, 0.867+0.128 −0.097, 0.725+0.080 −0.065} for the coasting models, while for ΛCDM Ωm,0 = 0.286+0.053 −0.047 and σ8(z = 0) = 0.764+0.039 −0.035. All models are consistent with the data, though the ΛCDM model is strongly favored over the coasting models, with log Bayes factors of log10 B = {1.79, 1.55, 1.42}. A predictive performance metric and posterior predictive check confirmed that while ΛCDM achieves the highest predictive accuracy, it also shows the strongest indication of overfitting. We also examined whether the S8 tension can be resolved by linear expansion for z < 2. Curve fitting yielded S8 = {0.890+0.024 −0.024, 0.865+0.024 −0.024, 0.850+0.026 −0.026} for the coasting models, resulting in ∆S Coasting 8 = {2.12σ, 1.21σ, 0.62σ} discrepancies with the standard Planck 2018 value. A value of S8 = 0.746+0.041 −0.039 was obtained for the ΛCDM model, indicating a tension level of ∆S ΛCDM 8 = 2.00σ.