As
ThermionicScott said, bike tires are basically a circular in cross section. They don't do any of the special molding and shaping that your automobile tire get. Partly because it would add to the weight and make for a very hard riding tire as it would have to be strong enough to hold almost three times the pressure a normal car tire.
If you frame limits you in tire size and you don't want one of those shiny new cyclocross bikes, then your best bet. IMO, is to look for tires that are geared more for speed and less rolling resistance. Those will naturally have a more supple feel to them and will give you a more comfortable ride. You'll give up some amount of puncture resistance, but the feel is wonderful.
In every case where I bought a more expensive tire than before, the ride feel improved even though they were the same size tire.