$str = '175/60 R15';
$str2='5,5 x 15 ET45';
function myfunct($sym = [],$str = ''){
$editString = str_replace($sym, $sym[0],$str);
$result = explode($sym[0],$editString);
return $result;
}
$result2 = myfunct(array("/"," "),$str);
$result3 = myfunct(array("x ", " ET"),$str2);
var_dump($result2);
var_dump($result3);