Yes soft tires makes obviously expected to have a lot of grip and increased wear, but I would also expect them to suffer more from overheating, while also having a greater risk of overheating. By the way I have also read one study which stated that tire that is massivley overheating, can melt the very surface of the tarmac at that instant moment and by doing that reducing adhesion massively. So the grip loss while overheating may not come only from tire. By the way slip ratio is how longitudinal way to transmit forces is described, that is acceleration and deceleration. Way of transmit lateral forces, such as cornering are described by slip angle.