ok i have a little complain dunno if this was suggested beforce and i don't care either, but i think the sand next to the curbs should be the same height because it makes you often crash and that sux a littlek
and the sand doesn't have the same density as the curb, therefore even after each race refilled it'll be worn out pretty soon.
So restrict yourself to some "known" curbs and try to drive fast AND clean.
The problem with that corner is not that the sand is lower then the curb its that the inside edge of the curb is not also worn down with smooth rounded edges. That curb would destroy a real tire and wheel from the shear impact alone. I popped the beadseal on my truck going only 30mph on suck a curb in real life. End result was a flat tire.
From watching the BTCC today at Snetterton, there seems to be a similar issue with the kerbs there. The grass on the far side has worn down, leaving a height difference that kicks them onto two wheels if they hit it wrong.