Thanks for the input. I will have to check futher. The following should add additional clarity (I hope).

This 85 does not have abs.

If there was air in the line(s) I would expect some spongy-ness, which I can not detect.

If I had a froze-up or corroded caliper I would expect each wheel to lock / not-lock differently with some pulling to one side or the other, and have at least one or more of the wheels to lock up. I have a slight drift to the right with the operative word being "slight." This may be a clue I'll need to look at.

I use both a summer tire and a winter tire and have the same experience (i.e. no lock-up) with both on dry pavement (asphalt).

My summer tires are Winston "Winner" LT235/75R15 with a non-discript highway tread design and have a 7.5" width on the ground. I see nothing unusual here.

My winter tires 30x9.50R15LT (Grand Auto) with mud tread and a 7.5" width on the ground. These are larger than the standard "235" but seems to me ought to lock-up.

All my subsequent stopping trials were sans any trailer and in 2WD.

Usually when pulling a trailer in the winter, and especially when the roads are wet, I'll lock-in the front hubs and then if I need to stop "hard" I can shift into 4WD on the fly and have all the wheels pull the same (or lock-up the same as the case may be, which has not happened yet).

I am getting a sense that the 85's just may not lock up.

Anyone see a flaw in my logic so far?