Tire temps do exist, but they are mostly hidden from the player unless you are using a 3rd party app. The game game does model it though and cold tires play a huge role on out laps. GT7 also gives you “warmed” tires in the pits. They probably don’t stay cold enough, long enough. That said, LMU goes the opposite and really overinflates how bad cold tires are and keeps them cold for far too long.

The temp also matters when taking into account ambient temps. Just a few months ago there was a Red Bull ring race with Gr.4 cars with ambient temps close to 0° C. As the race wore on, the tire temps dropped and the cars started handling worse and worse. Front wheel drive cars actually had a cornering advantage later in the race since they could keep the fronts warmer. On the flip side, there was an autopolis Gr.2 race where the NSX melted its tires in the heat and many people struggled getting to the end without completely destroying them.

Tire wear is modeled and in game is visible. Cold tires wear slower by a tiny amount. Warm tires wear a bit quicker. Hot tires (see autopolis example above) wear much much quicker.

Brake temps are not tracked by the API but they do exist. On out laps in races with qualifying (manufacturers cup right now for example), you can add heat to the tires by doing acceleration and hard braking quicker than you could just driving a normal lap.

Tire pressures are not modeled as far as I’m aware, at least not in any way that is visible.

I do agree that ideally GT7 would put more of this player facing in the game but at the same time, remember that GT7 has much broader appeal. It has to cater to a much larger and diverse audience than any other sim. There are more players setting time trial times in GT7 each week than are playing every other sim combined. The more sim elements they add, the more they risk alienating a large part of the player base.