The reason I ask this is the Goodyear RV tires selector lists a G670 for RV use. I have seen some of our Big trucks come withthe Goodyear G399 which had the same axle rating as our coach of 23,000 lbs. The price on the G399 is less that 500.00 each, with date stamps less than 2 months old. Need some advise as this will be our first tire replacement on this unit which currently has OHTSU RX148A tires that are 2005. They still look brand new but do not want to take any chances of having a failure.