I recently changed mine at Hup Shun SS3 but different size from yours. Mine are 245/40/18 & 265/35/18 on my F32. I went into Goodyear Malaysia website and contacted almost 10 different branches to get my staggered set up. Put the stock availability aside, even the prices are very much different every shop. Some are reasonable, some are expensive by almost RM1,000 per set, therefore you really need to make your enquiries to ensure you get the best offer.

The performance of the tyre, I am very impressed. I have driven to Penang and back to KL twice since change, experienced both dry and wet conditions and indeed it feels like the rubber grip is excellent. The car feels as if it is holding the road surface better and better at higher speed. I previously used PS4, I have to admit that Asmy5 is slightly more comfortable. Is the grip better or worse than PS4? Honestly I can't tell. Both are very good tyres in my opinion and on par.

Only downside is that the price is similar to PS4 or even more expensive quoted by some shops. And as you questioned, stocks are hard to be found. I will have to see how is the wear (PS4 lasted only 15km for front for me) and decide whether to stick to Asmy5 or back to PS4 or try MC6 next round. If the wear is better than PS4, I think I have found my fixed tyre model until a better one is introduced.

Those sizes are still not stretched actually. Probably camber setup a bit high and/or driving style more aggressive. PS4 normally at least can last up to 40k km.