As others have said, rapid rear tire wear is a fact of life with rear-drive mid-engined and rear-engined sports cars. That said, there are things you can do to minimize tire wear. First thing I do before swapping in new rear tires is to get an alignment check. Too much rear camber will increase wear. Tire pressure is also important, you need to monitor it every week or two and keep it correct. Over or under inflation will cause uneven wear and premature replacement. Driving style is obviously a factor, but IMO, Porsches are meant to be driven hard and if you're going to tiptoe around to avoid tire wear, you'd be better off in a Toyota :) .

Tire selection is a major factor. Kuhmo's are cheap, but from my experience, they require frequent balancing. I suggest doing a road-force balance to start with to minimize re-balancing issues through the life of the tire. Pilot stick great but wear like erasers. I've had extremely good luck with Goodyear Eagle F1 GS-D3 tires. They wear well, stick great in dry or wet conditions, stay in balance, are reasonably quiet, and are cheaper than Pilots. This tire may be or is already phased out by Goodyear, hopefully, they're offering an improved replacement.

It's all about the cost
 

New Porsche recommended tires will cost you, say, $1000 to $1200. They ride nice have a very good grip and last...maybe up to 40,000 miles. Most Porsche drivers like it a little on the fun side...that's why we buy a Porsche. I just installed Falken 912's on mine and so far they are performing great. Now, I live in Florida and we have heat and rain which these tires are great for...not recommended for the snow country. I have 225x40x18 on the front 265x35x18 on the rear. Cost installed $604.00 at Discount Tires. :cheers:

If long lasting rear tires is all you're after, just buy the tires with the highest treadwear rating and get an alignment. It was said earlier that you could get another set of 17" wheels and run the same size all the way around but you don't need to buy another set of wheels to do that. I have a 2004 Boxster with stock 17" wheels all the way around and in the winter I run the same 255mm winter tires all the way around and have not experienced oversteer, I do run staggered tire pressures, though. When the rears get worn half way down just get the tires swapped on the rims, front to back.

For what it's worth...

I bought Kumho Ecsta ASX for my '01 Box. They said they had a 30,000 mile warranty and that's almost exactly what I got - 30,000 miles before I had to replace them.

I just recently put Hankook Ventus V12 Evo K110 on the rear but I've only had them on for less than 5k miles so I can't really give a good opinion how they are over the long haul. All I know is that I like them a lot. Great grip and a good price from Discount Tires.

:D

Um, seeing as how this is a Boxster forum and all.... shouldn't we be bragging about how quickly we wore out our tyres rather than how long our tyres last because we granny-drive them? :D

Interesting, why do you go with 255 as supposed to 225/45/17 which is cheaper and more appropriate? Not to mention your wheels are staggered it'll be interesting to see 255 tires on the front?