Do I really need four?

Yes, it is critical. The manufacturers of AWD vehicles recommend that when you buy tires, buy them in sets of four and try to even get sequential serial numbers. At the very least, get them from the same batch. The reason is because AWD vehicles have what's called a viscous coupling instead of a transfer case. Even slight variations in tire diameter front to rear can burn the viscous coupling up. I've seen it first hand on an AWD Durango. This is why I always recommend people go 4X4 instead of AWD. Like Kitty's Escape. It's a 4X4 Escape, not an AWD Escape. They make both. Kitty's car has a bonifide transfer case, not a viscous coupling.