Hi there, I've tried using a fine 120 grit sandpaper on the rear tyres of two cars I've had for about 15 years but my cars still slide around the track and generally squirm and struggle for grip even when on straights. Please may you recommend some replacement tyres if that's what's needed? The cars are C2467 (Police Vectra) and C2118 (Subaru Impreza). Also, do you know where I could source a replacement headlight for the Subaru? I've spoken to a local hobby shop who recommended getting "Classic GT Tyres" but I can't find anything matching that description on any websites including eBay. Many thanks! https://i.redd.it/n418pm9uaq481.jpg