No problem ... The ST 115's are quieter than the Pirelli Assimetricos they replaced, and are MUCH quieter than the Toyo Proxes that I ran on another car about 4 years ago. BTW, I really liked the Toyos a lot, and would buy them again, but they were LOUD back then.

Do a search on some of the tire forums on the ST 115's. There are a lot of favorable comments on performance and silence.

 

The tires you can use are limited by maker unfortunately....for example in 19" combo for your C4S 235/35/19 and 315/25/19 you can only use either Continental or Michelin, both of which ride great but the Mich is a PITA to balance....

in 18" you would have a couple more options.

 

if you are worried about the harsher ride with 19's then get pss9s and dial in more coosh ya it's more dough but it's an option. row is not that much stiffer than oem so maybe you are sensitive to a rough ride.

i have 19's and coilovers and with the local road it's not bad. driving in downtown SF though is a nightmare!

tire choice is critical too. i ride 19" bridgstone so3 and the ride is much smoother than the POS 18" conti SC2s. i think i'll go with MPS2s next time though.

 

my experience, u'll feel little difference from 18'' to 19'' because ur mind tells u 19'' looks much better & the ride is ok. u'll feel big difference from 19'' back to 18'' cuz honestly the ride will be a lot better. not against 19'' but it's my honest opinion.

 

thanks for all the inputs. it is scary to think it can get even stiffer and louder going to 19s. getting PSS9 would be a good idea, but not sure i am ready to do so much right now.

another option is to get 18s. but always thought that you get bigger ones when going aftermarket!

well keep thinking.