Hmm, i was just playing GT4 about an hour ago.
It isnt really tire physics related, but get him to send a very front heavy car over a jump, front stays up in the air even when the rear of the car hits the jump. it doesnt change attack angle at all.
also, maybe, tune one of the GT4 cars to the same spec as say, the XFR (i used a polo gti :shrug
and compare the two games side by side for feel, and physics, it REALLY shows how much more superior LFS is!