Dude, you really need to understand that GT5 needs to match Forza's level of tyre simulation, and no it's not just above arcade sim racing, it's a bit more clever than that.
Its driving physics are hardly any better then Need For Speed shift. Both series belong in the arcade/sim category as did GT up until they released that demo at Christmas time.
Well why the hell would it need to match even Forza then? Why have tune-able components and not have something as important as tyre pressure? What about the weather affecting tyres then?
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Why even implement tyre pressure settings when the driving feel is so bad, it doesn't even come close to actual racing sims let alone real life.
I'm not sure what point you are trying to make. Are you saying you know a lot about tyre physics and thus you know Forza's tyre system is crap? Or have you just read that in a forum? If it's the former, how can you say tyre pressure is not important? Have you ever raced or tracked a fast car?
I've driven cars that make your M3 look slow, multiple times at Eastern Creek and Oran Park in Sydney, but thats not the point. The average fan of the series is not interested in the aspects of tyre pressures. They'd rather the game already implement the ideal pressure automatically.
I'd like it in the series, but I highly doubt its a big one on their agenda, although it'll more then likely be implemented. The biggest issue will be with the dynamic weather. It will be extremely hard to adjust settings on the fly by contacting the pit crew.