You know, for the last 15 years I’ve written about tires, mainly trailer tires. Mostly in RV forums and an unsponsored blog. My feedback in likes and dislikes are about even so I’m not much liked in the things I say about tires and how they are supposed to be used. My information comes from government regulations and tire industry standards. I don’t say much about tire manufacturers because I seldom write about substantiated tire failures. That’s the kind someone has actually proven failed because of a known cause. Even known causes are difficult to point a finger at because the causes may, in fact, have been errors knowingly or unknowingly caused by the owner.
We - consumers - don’t know any more about how a tire is made than what their manufacturer’s want to tell us. We know the basic materials used in the carcass construction. They are printed right on each tire’s sidewall. We know the tire’s load carrying capability - what their manufacturer tells us - because it’s also on the tire’s sidewall. What we don’t know is what the treads composition contains other than the basic materials. We don’t know the tread materials density, unless we have a durometer. Even then we have no idea what chemical concoction was used. Not even the percentage of recycled tire materials used in our new tires. It’s confidential.
I write a lot about the tires provided with Keystone trailers. I’ve owned one for 14 years. They, like all other large manufacturers of RV trailers have had their dark years with tire selections. They went with ST then to LT and then back to ST. Now with the heavier trailers they have gone back to LT (Hybrid) for their 7000# GAWR axles. However, there are newer and stronger ST tires cursing into the country from aboard. So, there is no reason to change designs. ST tires are soon going to fit all RV trailer axle configurations.
Have you ever heard of Keystone or FR recommending LT tires for ST replacements unless they had already offered them as options? They just cant build thousands of trailers fitted with ST tires and then switch to another design. Why? Because they said the ST tires on all of those trailer’s were appropriate fitments by design. Recalling them because they were no longer appropriate would cause enormous trouble for the entire RV trailer building establishment.
I’ve always been surprised at the average number of RV trailer owners that know nothing about their trailer’s owner manual. I’ve always kept mine in a book rack just inside he trailer’s entrance door for quick reference.
Below is the 2016 generic copy for keystone trailer’s. Tires, axles and all other associated info is in chapter 4. Because most of that information is mandated by NHTSA it's pretty standard stuff for each manufacturer.
http://www.keystonerv.com/media/3003...17_revised.pdf
There are basic vehicle safety features that the government wants standardized. Tires, rims, axles and their load carrying capabilities are just a few. When the vehicle manufacturer fit’s the Original Equipment (OE) tires to a trailer it’s not done by manufacturer. It’s done by size and load capacity that at a minimum must support each installed axle’s GAWR. The tire industry standards supports the vehicle manufacturer’s OE fitments and does so with their SOP manuals and PDF forms found on the internet. Below is the way one of those manufacturers says it.
Help Me Choose The Right Tire | How to choose tires | Michelin US
Most RV trailer owners want to “plus size” their tires when it’s replacement time. It’s very important to use a tire retailer that knows ST tires if that’s what your OE tires are. The goal in proper plus sizing procedures is to insure the replacement tires fit the vehicle - wheelwell and distance between tires - and they provide a load capacity equal to or greater than the OE tires by inflation pressures. The plus sized tires must be fitted to the appropriate rim size with the capability to support the trailer’s GAWR values and the inflation pressures to carry that load.
Bottom line; Don’t confuse durability with strength (load capacity). Most ST tires lack the durability seen on commercial graded tires. Those tires may have much taller treads - for long mileage - more dense tread compounds - for long mileage - an extra steel belt - help prevent punctures - sidewall inserts - to prevent failure from curb striking - retreadability & regroovability & steel casing - longer life cycle.
This is a quote from a NHTSA interpretation. "Industry standards generally form the basis for demonstrating product safety and quality before courts, regulators, retailers, consumers and others."
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