2015 Camry's Michelin tires "softer"?

OK a couple of items:

  1. Yes, siping increases rolling resistance but not enough to worry about.

  2. Read here about OE tires: http://www.barrystiretech.com/oetires.html

Short version: OE tires are designed to the vehicle manufacturers specs - and typically those emphasize fuel economy - and they get that by sacrificing treadwear and/or traction.

ALL - let me say that again - ALL tires that come on new vehicles are specially made to the vehicle manufacturers specs - no exceptions. They are NOT like the tire that you usually get from the local tire shop - except to say, you can buy the OE tire there.