Here is a simple way to use old car tyres to make useful and weather resistant rack for your bicycle.
I want to save top layer of earth with grass so I carefully cut it.
Then I dig a hole shaped like "U" letter sized by tyre.
Put tyre inside, fill it with earth, and put on top earth layer with grass.
Distance between two tyres was 5cm or about 2 inches.
ckausb made it!