I think I ran into that looping tyre sound bug once myself, but it was in a multiplayer game where I'm pretty sure the host got disconnected. The sound in general does seem to be a bit much, though I think it may be another one of those things that's cropped up because I was well used to steering the car before I even added it in: I suspect it's much more grating if you're frequently taking more than one full circle to make a turn, rather than hearing it only briefly on each corner.
A bigger track is a neat idea. I did consider it while making this (particularly as the Kenney racing pack seems to include assets for wider corners), but by that point it would essentially have meant building a new one from scratch. I'm also not positive how it would affect the gameplay: chances are it would mean less running into walls, but it might also offer rather a long way to drift off course. But if I added more tracks to the game, having some wider options would be one way to increase variety if nothing else! The balloon battle idea is an interesting one too. I feel as though it would probably require weapons/powerups that might mean a departure from the two-button control scheme, but at the same time I can imagine forcefields, orbiting drones, melee weapons popping out of cars - the sort of thing that might be activated on pickup and then simply remain in play until it timed out.