Like all drivers, I do nick my tyre sidewalls now and then when I take a turn too fast. Whether on a multi-storey carpark ramp or mounting a kerb elsewhere. Well the last time I nicked my rear tyre, it caused a cut in the tyre sidewall. I didn't think much of it cause it looked superficial and most importantly the tyre still works fine without any deflation.
From what I learnt recently, that's not the half of it. Having a cut on the sidewall can be a serious hazard. When I brought my car in for servicing at a workshop that specialises in (of all things) Lambos, Ferraris and Porsches, the mechanic told me to get my tyre changed asap. Reason being that the layer of rubber on the sidewall is thinnest there. The main purpose of it is to keep the tyre upright while it has air in it and also to keep it from coming out. Having a cut in the sidewall compromises the tyre's integrity and might cause a sudden deflation if you have a particularly hard bump.
That doesn't help me at all because now I feel as if I'm driving around on a timebomb till I get my new tyres. *shudder*