I check the website got your size...
Your size in Malaysia mostly consider special/rare size, they need to order from oversea also.

http://www.y-yokohama.com/product/tire/advan_db_v552/
235/45 R 18 94 W

http://www.y-yokohama.com/product/tire/bluearth_a/
235/45 R 18 94 W

Continental no need see, most of the tires are high performance under UHP for your size. So comfort is out of range.

https://www.continental-tyres.com.my/car/tirefinder-my

Continental either got MC5 or CSC5 for your size only for local market.

At least for Continental get the CPC series (maybe only CPC2 here). MC6 is supposedly similar or even better than CPC2 but not sure really coz not much reviews on it. UC6 is low end model, should be comfortable but grip is not good.

I also check Primacy 4 is not yet having your size in the Michelin Malaysia website, not sure if really don't have or not coz often the website is not really complete/updated. If available, I think this should be your best choice but will be quite pricey too.

Oh maybe you can also ask around for the newest Hankook Prime 3 (K125), that should be a decent mid range tire with much more affordable price than Primacy 4 or Turanza. Not sure if already available in Malaysia market though.

MC5 not so good, and he's using it already now and seems looking for a change.
CSC5 is excellent but very expensive and not so silent so probably would not be suitable for him.

Official website don't have ventus prime 3, so likely not available yet. Mudah website also don't see any listing.

Don't want to promote your favourite v12evo2 kah? Got 245/45/18 size

Nope, coz I think that size will make it heavy for his car. Even I don't want to use 245/45/18 on mine so I wont suggest it to his. Actually for his exact size the best value tire would be the FK510 but he doesn't like stiff sidewall tires so cannot suggest that anymore.