I've had vibrations on my 06 TSX and my 08 RDX that just wouldn't go away until I did a cross rotation of the tires (left to right OR right/front to left/rear etc...). I drive my TSX pretty hard in the corners (Aspec suspension, Progress RSB, Fastline endlinks, HTSpec front/rear ultimate camber kit, OEM size Conti DWS non-directional tires). My left front tire gets the most wear on the outer edge, while the right rear gets the least. Rotating and then cross rotating every oil change seems to smooth out and vibrations I feel in the steering wheel (usually front tires) or in the driver's seat (usually rear tires).
I had Bridgestone 960 directional tires on my TSX before the Conti DWS and I couldn't do the cross rotations. I couldn't get rid of the vibrations 100% with only a front to back rotation with directional tires. I also had to switch tires sooner because of the extra wear on the outer edges on the left side of the TSX.
Another solution is to try a road force balance of the tires. Discount Tires in my area can do this for free if you purchase the tires from them. They apply up to 1200lbs of force to tire/rim combo to find the hi/low spots and adjust the tire on the rim to minimize balance weights. It can sometimes turn a +60 mph vibration into smooth as glass feeling. May not work as well if your tires have a lot less tread or irregular tread wear pattern caused by any undiscovered suspension issues. The newer higher speed spin balancing machines may not work as well as the road force machines to remove those annoying vibrations.
Son - 06 TSX 5AT w/ Navi, Carbon Gray w/ Quartz (handed down for 16th B-day Mar/14)
His - 08 RDX Tech, Moroccan Red Pearl w/ Taupe (finally replaced Takata airbag on 6/16/16 after 86 days with rental)
Her - 11 MDX Adv/Ent, Palladium Metallic w/ Ebony