Had my tyres replaced finally. Was supposed to go for Goodyear Assym 5 but ended with Primacy 4 ST that had a promo (only $100 more than the Goodyears).
The set of Primacy 4 ST is made in Thailand. I am not sure what is the difference between Primacy 4 and 4ST other than the "ST" means silent tread (i.e. quieter?). Wrote to Michelin asking about the difference between the two and they could not come back with anything convincing either. Btw, the Primacy 4ST has "Primacy 4" imprinted on the side wall as well (unlike the Primacy 3ST which has the "ST" suffix). However, the Primacy 4ST does have a small (almost non legible - as small as the DOT dates) "ST" lettering found about 180 degrees from the Primacy 4 wording.
How do I find the tyres? I find it quieter than my changed out Michelin PS 4. Other than that, I think PS4 is a much better tyre in terms of handling and steering feel. For the first 2 days, I was very disappointed with the new tyres - felt wobbly and hesitant when driving above 100km/hr. Found out subsequently that the tyre shop had actually over-inflated the tyres (was at 41psi vs recommended 37-38psi). Felt much better after getting the pressures right - but still doesn't feel as good as the PS4. Noticed also that the fuel consumption has somewhat increased with the new tyres.
I have done 1500 kms on them since.