Taller (longer) gears might help a little. The best approach to conserving tire life will be smooth driving and correct braking... and judicial throttle use
Since the update I lubricate my tires with my tears.
But seriously, corner technique and throttle are better bets than gearing. Though I suppose that could help as well. I also use TCS with torque-heavy cars like the 908, which would use TCS in real racing anyway. I keep it between 1 and 5 depending on where I am in the tires.
Gearing should be adjusted according to the track or, for the GT5 drag racers out there (), for acceleration. Manage your throttle better and you'll see a huge improvement in wear.