I am running the Goodyear 295/80/22.5 16 ply rv tires,  I did have Goodyear install 2 new fronts shortly after buying our rig a little over a year ago.  The rears are the factory installed tires from 2006.  They still look OK to me, but I am certainly no tire expert.  I know we are pushing the 7 year time limit, but have only 40,000 miles on the rears and about 10K on the new fronts.  Do you think Schwab would look at my tires and give me a report on condition, or with the age, should we just change them?  While at the service center in bend last week,  I ask for a quote to change all 8 tires to the Michelins 18ply.  The cost was $6100.00 less a trade-in on my new fronts.