On a side note, I'm pretty sure that anyone using a DS3 is pretty much out of luck on wear compared to wheel users. It's just something I've noticed after all this time.
It actually depends on how you use the DS3. For those trying to get good tire wear with that, here are some things I figured out.
Tuning:
Really, I have no clue.
Acceleration:
Don't have the throttle mapped to a switch or button. Map it to the analog stick or R2. R2 and the analog stick will allow you to smoothly apply throttle. Spinning tires = horribly tire lag.
Braking:
Reduce the brake bias and don't use full brakes. You rarely ever need to go full braking power. Just brake to what you need, and a little less if you want to conserve your tires.
Steering:
Biggest thing a lot of DS3 users do wrong is just throw the stick all the way to the left and all he way to the right. This destroys your front tires. The speed that you can go from lock to lock with the controller is faster than with a wheel (normally. You can whip your wheel around to beat the controller, but it feels so unnatural and you can feel the speed/tire rubber being lost).
Don't use the extreme left and right - try to be as smooth and slow as you can and still make the corner. Never just let it snap to center. If your tires glow red, back off immediately.
Tire Temperature:
I'm still experimenting with this. I'm starting to notice a pattern. The tires get to hot, they lose grip. Then you start diving into corners harder and using more steering to compensate, resulting in horrible tire life. Best thing to do is to keep the tires below the optimal temperature (I have no idea what it is). But if you can find it, don't push beyond it, and if you feel the car losing grip, don't try to make up for it - let your car slow down and cool the tires.