Here is my purely un-scientific explination based on my observations...
Folks want to...
1) drive way to fast while towing. ST Tires are rated for 65 MPH, you shouldn't run anything at max all the time, let alone exceed the rating.
2) don't understand and check tire pressures like they should. This is almost epidemic and why the government felt TPMS shuold be mandatory on passenger vehicles.
3) don't understand their specific tire/RV weight limits and run them overloaded.
4) Look at tread life and equate that too tire life. Tires, especially ones that sit most of their life, need to be replaced ~5 years after MFG date regardless of miles they have been used.
I think its these primary reasons that RVs experience most tire issues. Now Goodyear appears to have the most market share, and therefore will experience the highest number of actual failures, but probably statistically insignifcant when compared at a % of actual failures.
I have been running "China Bomb" GY Marathons with no issues todate. Based on date code they are ~3 yrs old.
