We could open up a whole can of worms talking about tires. So many have had issues with the stock tires that come on the rvs these days, others have not had any issue. We aren't sure why our tire blew...we personally think it's probably a combination of being driven from the factory in Indiana to Texas, being on their spare storage lot for a few months, possible under inflation and possible speed by the driver or he could have run up a curb. We just don't know for sure. We weren't savvy enough to have them check tire pressure in front of us during PDI which I now recommend to anybody picking one up at a dealership or having one delivered for them, like we did (didn't have the truck until 3 months after getting the 5er) DH did lots of research on tires and he said every single brand has good reviews and bad reviews so he went with what we could afford and that had a reasonable probability of being better than the stock tires, so he got Goodyear Marathons. You'll read good and bad reviews on those and I'm not familiar with the details of the tires. I only know that he went by what is recommended on one of the stickers on the 5er.
As for replacing yours before your trip, that's a good question. Since DH and I are newbies, I can't really give advice from our other experiences, as who knows...we might have been able to get lots more mileage off the stock tires (which were Westlake). I just know that we had been reading lots of bad reviews on the "China bombs" as they are affectionately known, ours arrived to the storage lot with a blowout and we wanted to err on the side of caution as we are hoping to spend LOTS more time traveling in the very near future.
Best of luck to you...post pics (we all love pics here) and can't blame you for wanting to escape this Texas heat. We just spent this past weekend camping at Lake Tawakoni State Park and it was hot! HOT!
2015 Coachmen Chaparral 360 IBL
2014 Ram 3500 Turbo Diesel 6.7 4wd Crew Cab Dually