Rear D-Ring bolts question

[sclui56]

Just want to get a definitive answer on the length of these bolts. The standard bolts holding the D-rings are M12x1.75x55, while the ones used to mount the D-rings for a tire carrier equipped H2 are M12x1.75x65 (same as SMA as well as the SUT).

Question is - I used the original M12x1.75x55 and mounted the D-rings assembly for a tire carrier b/c I didn't have access to the longer 65's. After everythig was secured & torqued to approx. 85 ft/pound, the exposed thread inside the bumper is at least 1/2 " in length, and the rule-of-thumb I was taught long time ago is that the minimum required left-over thread should be sufficient for at least 5 complete turns, so 1/2" is certainly more than that.

According to the above, I fail to see the benefit of using the 65's b/c the extra length is not holding onto anything more than the 55's did, yet SMA basically said it's unsafe to use the original 55's.

Am I missing something?