Supply concerns kept spot rubber firm on Thursday. RSS 4 improved to ₹132 (130) a kg according to traders. The grade firmed up to ₹131.50 ( 130) and ₹128.50 (127) respectively, according to the Rubber Board and dealers. July futures increased to ₹132.50 (131.90), August to ₹137.50 (135.30), September to ₹138.97 (136.17) and October to ₹136.75 (135.69) on NMCE. RSS 3 (spot) closed at ₹108.86 (108.55) at Bangkok. July futures weakened to ₹107.33 (108.87) on TOCOM. Spot rubber rates (₹/kg) follow: RSS-4: 132 (130); RSS-5: 130 (128); ISNR 20: 125 (123.50) and Latex (60% drc): 93 (93).