Hey JJ,
Since your coach is a 2009, I would suspect age could be playing a role in your tire problems along with sidewall damage from the sun. Check the date code on the tires and start using covers on them. If they're China bombs, you may want to replace with some G614 Goodyears, or Michelin LT's.
A fulltime friend of ours in a toyhauler replaces one or two tires a year, but continues to use cheap tires and won't cover them. Unless you're under a bunch of trees in Lancaster, I don't know how you could only have a few minutes of sunlight on them daily????
Regards, Hamshog
2009 Silverado 2500HD EC/SB Dmax/Alli - SuperGlide 18K - Firestone Bags - 265/75R16's -
2010 Carri-Lite 36XTRM5 w/ Big Foot - Champion 4000W
2005 Harley-Davidson Road King Classic
2005 Jeep Wrangler Unlimited LJ
2007 Fleetwood Pegasus Ultralite M-180FQ