Height of the curb when paving

Good morning!

For the edging of the pavement or splash guard: How high should the curbs be? They come from 10 - 30 cm. Is 15 cm enough?

If I set 1/3 in concrete, there are still 10 cm left for backfilling with gravel, or if the pavement is 8 cm, then only 2 cm for grit. Preferably 20 cm? Or even 30 cm?

The price difference is negligible, but I imagine handling stones over 40+ kg would be unpleasant.

What do you have?

The higher, the more stability you have. We took 30 or 25 cm, I think there were no lower ones at the hardware store... And where the car drives over, we were recommended 8-10 cm wide instead of the usual 5 cm.