Under the PP system of selecting cars harder tyres in the right mix can be very useful in saving Performance Points. Turn it into power to compensate for any traction loss. Such a tyre tune can be useful in this and other circumstances, I've met these:
FF: some cars are way faster on softer fronts with 3 steps harder rears, Honda Type R can be a hoot to drive with this tune, Great on any track won on speed out of corners in this marque.
FR: some FR cars can only have their front ends tamed by a 1 step harder front, these are usually longer wheelbase cars with a lot of grunt and aero. See MR, similar suspension issues there, but the reverse solution. See Tom's Castrol Supra and the like, in enduro races can work as a strategy in quality hands, worth testing. Hard fronts on the Ford GT 40 LM when you know the car really well say at Fuji F, or anywhere really, (I lift the front height of the car 3 points, the combination can tame the car). Howler, but there are much faster 850PP cars out there than it. The LM in GT5 is likely a great club racer.
AWD: I've come across Evo X tunes that were very fast in expert hands, had 2 x harder rears. Scary. Nissan GTR modded road cars in certain tunes cope with harder fronts (jack the rear LSD up though, and get it straightish before you fire it), very quick. I've seen the reverse tyre balance in the GTR be quick in some hands.
MR: some drivers find the front end of the Merc GTR MR need 1 x harder, you need to be very accurate with lines while driving this balance, but the front grip weakens and lessens the danger of the Merc's torque twisting you arse about, and tyre wear front to rear strikes a better balance. Nothing special, but I've managed low 5.40's in it round the Nordschlief with those tyres. The Audi R10 can work this way on some tracks (bit of a mood thing that one).
Tyres on different corners wear at different rates on certain tracks. It would be a nice, but unlikely game mod to be given control over the rubber on every corner of some cars. But that's more a dirt speedway kinda thing I suspect.
Testing different grip front and rear has it place in any thorough tune if you get deep into a long second long and there is still a balance nag.
Different strokes for different folks.
Good luck
