I am on my second set of 19.5 Michelins. The TC I have now is not quite as heavy as the one before but still gives me a lot of confidence when out on really boney roads or hit spring potholes, frost heaves at high speed.
I am not a sand guy so airing down is not an issue. These H rated ,medium truck tires definitely are more heavy duty than your average OEM "E" load tire for sure.
One more thing to remember is my spare ( 275 R70 18)is still one of the OEM tires and although the diameter is almost the same as the 19.5, the wheel nuts are different so if you are to keep the original spare, bring along the 8 original nuts.
I have had no flats or issues with the two sets of 19.5,s from day one.
Dave