'15 origional Tires replaced causing humming sound
 

Ho Guys,
my 3.6 Journey just over 66Kms had first time original tires replaced by the new Korean tires, I noticed while driving first time on the highway after replacement that there is a little humming noise which was not there before at all.

any idea? also how much KPI (air pressure) should I maintain in summer?

Thanks a lot.