Question 900965
He would start with this pattern:

1 2
3 4 - S

keeps them on until {{{ x }}} km driven

2 3
4 S - 1

on car until {{{ 2x }}} km

3 4
S 1 - 2

on car until {{{ 3x }}} km

4 S
1 2 - 3

on car until {{{ 4x }}} km

S 1
2 3 - 4

on car until {{{ 5x }}} km
----------------------
{{{ 5x = 500}}}
{{{ x = 100 }}}
Each tyre covers 100 km