Maybe you should get 2 sets of tires. One for the wet season & one for the dry season. That's what they do in Canada, except it is winter tires & one for the snowless seasons.?
thighland is very different from canada. in the tropics, you can have rain for one hour and sunny dry weather the next hour. no point changing tires like changing underwear. whether it's the monsoon or drought, it's always wise to have newer tires with adequate treads. even with new tires, regular rotation is necessary to ensure tire wear is not extreme or unbalanced on an edge. the reason i'm using
dws tires is because in northern california during winter, i can encounter snow in the mountains, rain and wetness along hilly roads, and dryness closer to the bay, all on the same day. seasonal changes are not as drastic as in canada, and thus there's no need to keep 2 sets. for the tropics, i'll recommend tires that can handle rain all year.