Posted by Ben on October 13, 04 at 15:09:37:
In Reply to: Re: True but... posted by Dave'02LT on October 13, 04 at 14:40:30:
Most who only use their trucks as "cars" don't need LT rated tires...but those who do tow should have LT tires.
There are basicly 3.5 classes of tires, as we know it. Lowest are passenger car tires with the "P" designation. Next higher class are "LT" tires (Light Truck). Next are "ST" or trailer tires (these are higher rated than "P" rated, but not exactly "LT" rated. They are usually bias ply, but some are radial. Highest class are "commercial" for MDT (medium duty trucks...like the semi's out there). "Commercial" class tires are in the "half" inch dia sizing (16.5, 19.5, etc) and do not have safety beads in the bead area.
Reason for half ton trucks is that the GVWR range is so great (which vary from +6K lb...+7K lb....+8.6K lb GVWR). Even for the +6K lb GVWR, when they tow heavy, they should go to the next higher rated class tire.
This is because of the need to manage that "push" that comes from towing anything. Some call it "sway", "wiggle", or ???
Like going around a curve and hit the brakes. If the TT's brakes initiate and grab evenly, the TT will want to go straight. The TV's tail will get a "push" wanting to push it's tail out (oversteer). Or when going straight and hitting the brakes and the TT's brakes unevenly grab, it'll want to go "that'a way", while you want to go "this'a way". Finally, the sway or push from the pressure/vacuum wave of passing/being passed by another with a large frontal area that generates this large bow wave (pressure/vacuum). The TT will want to "wiggle", "sway", "etc" back and forth.
All of this is taken up by both the TV's suspension and tires, but mainly the tires.
Having "ride quality" soft sidewalls won't do much to manage this. Stiffer, stronger sidewalls will.
In "ride quality", more than the construction and sizing of the sidewall and overall tire, but the relationship with the wheel too. Why I've gone to 10" wide rims. There is almost no sidewall bendback on mine, so the LT "E" rated sidewalls even stiffer and stronger.
The picture is of the old Goodyear/Ford try at a new tire type/spec back in the late 70's early 80's. Failure, but this picture is good one to show the relationship of sidewall bend back that I'm talking about.
Next post will have another picture that I was noodling/doodling around for a tire article was commissioned to write (ended up they didn't use the article).