Well, OOVEE "sold" (?) the game to Focus, so don't expect free update for a game not existing any more!
Can you imagine, that the new distributor want to earn money with the game?
But this is a chance for a new beginning and that should be supported by purchasing the "new" game
If you own the original Spintires on Steam, you'll be able to buy Spintires: MudRunner for 55% off.
This is due to a 50% loyalty discount for people that own the Original Spintires, and a 10% discount for pre-ordering. As Steam uses multiplicative percentages, this adds up to a 55% discount in total.