coming down a 25% grade dirt road the brakes started to smoke and fade.truck in low gear o/d locked out speed kept to 10 mph .we had to stop and let them cool at 1/2 way point ,dirt road 4 miles long...
If your truck is a dully,I had the same problem you most likely need your rear brakes adjusted do this at least before any long trip they do not adjust by themselves. Good luck.