The G614's I have are the same diameter as stock, just a tad wider in the tread.
I am running them at 90 PSi, as my 320RS really isn't that heavy. Goodyear has a chart somewhere online with recommended pressures depending on what weight is on the tires.
It is amazing to watch the pressure and temperature with a TPMS system. These new tires barely change, as the old E range tires would increase pressure by 15-20 lbs, and temp would rise fairly quickly also.
Steve and Vicki
2011 Dodge 3500 CTD Outdoorsman
2013 Columbus 320RS-ITS HERE!!