Originally Posted by Inland RV Center, In
When making tight turns with the trailer in tow, stop and notice the twist to the side walls of the tire.
Auto tires were not designed to take that, but the ST series will, without harm.
That being the case, now which one do you feel is better for the trailer?
The sideways motion of the tire in a double axle configuration is the same thing that happens in a car when cornering rapidly; the tire is slipping sideways.
This is of course much easier to see in a trailer, since rather than happening only when cornering vigorously it happens at slow speeds, and if you stop in the middle of a turn can even be seen statically.
The worst case condition would occur when the tongue is moved sideways; each tire would scrub sideways but not roll at all.
The minimum turning circle on my truck is about 52 feet; if we assume that there's an even weight distribution on both trailer axles, with the axles about 33 inches apart, each tire will undergo about 1.5 degrees of slip. This is well within the linear region of slip, which extends to four degrees or so for regular car tires.
Stiffer sidewalls produce more side force per degree of slip; this is why (besides style) wheels are getting bigger; as long as the suspension can cope w/ the reduced cushion provided by a low profile tire, low profile tires give more responsive handling in sport oriented driving.
The tire is not damaged by this slip other than normal wear; however, sidewall damage is
an issue for trailer tires - it's very easy to catch a curb w/ the trailer tires. Here the heavier sidewalls of an ST tire make sense - just as the heavier side walls of a LT tire compared to car tires make sense in 4wd situations.
Clearly, when backing and/or using the front hitch on my truck, these slip numbers will be exceeded. But tires have to be able to handle side slip - that's the only way to corner at all, and the trailer will spend a lot more time at highway speed than tight backing conditions on pavement.
My trailer came with Michelin LT radials originally, and that's what was on there when we bought it. I'm inclined to continue, esp. given the problems others have had w/ ST tires.