Tire woes -- big time

I have a 17 Cayman S PDK. Factors that determine wear are: 1. pressure (under, over, proper) 2. Alignment - caster, camber, toe in 3. Rotation - limited on 718's due to the fact that the front and rear tires are different sizes and cannot be rotated/cross rotated. I have Michelin PS4S (one series wider than stock) on the front/rear and am running Nitrogen. Nitro stays more stable throughout the year with temperature variations and the molecule doesn't "leak out over time" as much as regular air. The above factors combined can determine premature tire wear. I run 30-31 PSI cold and check them regularly. I ran Nitro in my Vette for 2yrs and tracked the stability of the tire pressure. All of these variable must be synchronized or you will experience premature tire wear. I know the Michelin tire guy who has a Cayman and he can run any tire he wants and he said he will be switching to the PS4S tires when it comes time to replace his. There are many good tires on the market - do your research, talk to a lot of owners who have the same car as you and choose accordingly. CHECK your tires regularly particularly when there are significant temperature changes and you should find you will get as much tread life as is possible. Take pics and post them. What pressure are/were you running? The harder you drive the tires the faster they will wear out - that's reality. I hope this helps you to find the tire you are looking for.... OH I almost forgot - if you have suspension issues that too could effect tire wear. I hope this helps!