I don't subscribe to the magazine, what exactly were the ways the rack stressed the wheels? I have a thule hitch rack, and I can't see it putting anymore stress on the wheels than just riding the bike would do.
Matt Phillips of Bicycling magazine writes:
YOUR HITCH RACK MIGHT BE DAMAGING YOUR CARBON WHEELS
“Not long after my friend Gina outfitted her Pivot trail bike with a new set of DT-Swiss carbon wheels, she took it to a shop for a tune-up. During service, the mechanic noticed distortion in the front rim, so she emailed DT-Swiss’s USA office and was told it was most likely caused by exposure to exhaust while transporting her bike on a hitch rack.
That got me thinking. I had noticed something similar happening to my carbon wheels. Twice, after just a 10-minute commute, the rim closest to my car’s exhaust was warped or buckled.
Until now, neither Gina nor I considered our car’s exhaust, specifically the location of it, to be the culprit. And if
we didn’t know, it made me wonder how many other cyclists aren’t aware of this potentially dangerous issue. Gone unnoticed, a damaged rim could fail midride and cause a crash. With more riders using hitch racks and carbon wheels, it’s time to raise awareness about this possibly life-threatening combination. So I did some digging.
I reviewed several owner’s manuals and found nothing related to exhaust. I also reached out to wheel and rack brands to find out if they’re aware of the issue and, if so, what steps they take to warn riders. Mark Jordan, a representative for Reynolds, said, “I have not heard any buzz that it’s a common problem for Reynolds.”
And yet some wheel and rack makers do inform users about possible effects of exhaust heat. Enve warns, “Ensure that the rim is well outside of 18 inches away in any direction from the exhaust pipe of the car. Similarly, the rim must be out of the direct path of the exhaust, even if it is farther than 18 inches away.” Russ Fogle, Lead Product Engineer at Rocky Mounts, agrees that it’s a known problem with all hitch racks, but says, “Unfortunately for us as rack designers, each model of car has its tailpipe in a different location, pointed in a different direction. If we were to design a rack to avoid one car’s exhaust, that would just move the rack into the path of another car’s exhaust.” And yet, several companies stated it’s more of an issue with trunk racks or hanging a bike over a pickup’s tailgate.
But if there’s one common thread, it’s rear-facing exhaust tips. “Rear-facing exhaust tips that line up with the bike rack and lower portion of the rim can do the damage,” said David Agaptio, tech services and warranty manager at DT-Swiss USA. Fogle suggests adding turn-down tips to redirect heat away from your rack and bike. Another solution is to add a riser or swing-away kit that safely spaces the rack away from the exhaust. My solution? I switched to a rack that positions my bikes higher up and farther back. Gina was able to replace her rim at a discount through DT-Swiss’s crash-replacement program. One new rack and three new wheels later, the lesson wasn’t exactly cheap for either of us. But if our experience can help others avoid the same issue (or even prevent something way worse), then in the end, it’s pretty much priceless.”
The article includes a photo of an obviously heat-damaged wheel, and a few options for people to buy (of course.)
It had me wondering why Jim Parker's wheel would blow while seating a new tire.
It also has me wondering if my
current rack or any other system where the wheels hang on hooks might cause premature failure.
...er picture? 
