Spot rubber regained strength following the moderate gains in domestic futures on Tuesday. RSS-4 firmed up to ₹139 (137) a kg, according to traders. The grade improved to ₹138 (137) and ₹135 (134) respectively, according to the Rubber Board and dealers. January futures closed firm at ₹142.25 (140.23), February at ₹145.70 (143.34), March at ₹148.94 (146.67) and April at ₹154.71 (152.70) on the National Multi Commodity Exchange. Spot rubber rates (₹/kg): RSS-4: 139 (137); RSS-5: 130 (128); Ungraded: 117 (116); ISNR 20: 124.50 (123) and Latex (60% drc): 83.50 (83).