I want to jack up my car so I can work under it. Sadly, the only non-inclined surface I have available is covered in grass paving blocks similar to this:
I have a pneumatic jack that I would use to lift the car up on one side, then I'd put these jack stands under it to secure it better:

But I'm worried that the jack or the jack stands might slip off the concrete onto the grassy bits, or maybe crack the somewhat thin concrete area, and become unstable.
What would be recommended to put under them to spread their weight over more area and prevent slipping? My best guess would be "thick wood" or "iron plate with a non-smooth surface", if there's an established "best practice" or maybe even a product to buy, I'd love to hear it.
Location is germany, if that matters.

