So I bought some Bridgestone Potenza S-03 Pole Position's from Tirerack (thanks for the tip on the great price deal guys!) and I originally intended to leave off putting them on until after I've stored it this winter and taken my '8 on a road course. Basically, I was thinking I'd get the most out of my current rubber before switching over.

Of course, now that I have the tires...I'm finding it difficult to hold off. From what I've heard new tires can provide a big improvement. Right now I'm riding on Dunlop 8090's that have maybe 5k miles to go if I rotate (rears are pretty low on tread, of course).

So, what to do?

I am in the same boat with the same S-03's. I am going to try and keep the RE040's on till Dec when I tend to mount my 17" winter rims. Then have the S-03's mounted on a cold winter day to give me a reason to get out of the house.

I just put the S-03's on yesterday (replacing the 8090's).
Honestly, if you don't have any track days scheduled until spring, just hold off on the swap and finish what's left of the 8090's.

Having a fresh set of Max Performance (S-03's) tires on instead of a worn set of Ultra High Performance (8090's) tires is a performance increase, but for daily driving, it's not going to be so noticeable. Don't lose any sleep over not having the tires on yet.

Cheers.

But first and foremost, replace your 8090's if the treadwear indicator is flush with the tread. Safety over frugality.

Oh no, I can still stick a fingernail pretty deep into the tread, even on back.

Would you say that, in new condition, that the 8090's are a superior tire to the S-03's? Even if they were a bit better, I'd be hesitant to pay ~$260/corner, esp. when I got the new tires for ~$130/corner.

The S-03's should provide a bit more overall grip. So far, in daily driving, transitional feedback is similar between the two tires.