Let me try an explain this, the best I can. The width of the tire doesn't matter, it's the sidewall height. The front and rear tires are rotating at two difference speeds, which is causing an imbalance within the transfer case. And the transfer case is trying to cope with the imbalance. Over time this will cause bigger issues if not rectified. Say if your were to do a very hard launch, you can theoretically destroy the transfer case, or as least the gear set inside it. And the bill would be hefty, I recommend replacing the front tires with the correct size. The transfer can only cope for so long, before things break.
But the choice is yours.