Originally Posted by BigDan1
have a 22 feet triple E class C
front michelins are due ,( loved the comfort but road stability so/so)
I would like to have more rigid sidewall for better stability
When you say "Michelins" (or any brand of tire), it is important to identify the specific MODEL
of tire, not just the brand.
In the case of Michelin, a Michelin LTX is a very different tire, with very different sidewalls, than say a Michelin XPS Rib, even when both the LTX and the XPS are the exact same LT225/75R16 size and Load Range E Load Index 115/112.
When uninflated and unmounted, so that the tire bead and sidewall itself can be grasped in the hand and wiggled back and forth, the sidewall of an LTX feels like a limp party balloon when compared to the sidewalls of an XPS Rib.
The difference is in the construction of the tire. The XPS Rib is a steel/steel tire, meaning that it not only has steel belts under the thread, it also has steel belting radially oriented in the sidewalls, from bead to bead. The LTX does not have steel sidewalls.
One can immediately tell by the weight difference between these tires. The XPS Rib tire (in the LT225/75R16 LRE size) weighs 50 lbs, while the LTX tire in the exact same size and load rating weighs less than 40 lbs. The weight difference is largely due to the steel in the sidewall of the XPS rib.
UPS tires means tires used on United Parcel Service delivery trucks, that are subject to lots of turning, lots of stops and starts, lots of braking and acceleration cycles, lots of tread scrub, lots of concrete curbing and sidewall scuffing... and not a lot of highway cruising.
While Europe is no doubt different, over the years and areas I've been in the USA, most UPS step vans are built on Freightliner MT55 commercial stripped chassis that utilize 19.5" tires, and all 19.5" tires have steel in the sidewalls.
It is somewhat rare for a 16" light truck tire to have steel in the sidewalls, even though most 16" LT tires have steel belts under the tread deck.
There are, however, at least 3 name brand LT225/75R16 LRE tires available in the USA that are considered "all steel", or "steel/steel", and have steel in the sidewalls wrapping from bead to bead. They are listed alphabetically below, in no particular order of preference, nor recommendation.
Bridgestone Duravis R238
Goodyear Endurance RSA ULT
Micheline XPS Rib
Note that all three brands and models of tires listed above have the following characteristics:
All 3 weigh 50 lbs each.
All 3 are 10 ply rated load range E
All 3 are Load Index 115/112
All 3 are Speed Rated Q, or 99 miles per hour
All 3 are considered "Summer" tires by their manufacturer
All 3 are Steel / Steel, with steel sidewalls
All 3 are Ribbed Steer tires, aka All Position
It is the "Rib" tread design (as described by donr103 in an earlier post), and the steel sidewalls, as I've explained above, that makes these three tires more like "UPS" stepvan 19.5" tires.
Steel sidewall tires have stiffer sidewalls. And both the stiffness, and the steel, can be a benefit for durability, as well as a problem in an RV application.
I have another vehicle with steel sidewall tires, and when that vehicle is unloaded, and underinflated, one cannot visually tell that the tire is low, because the steel in the sidewall makes the sidewall less flexible, so the sidewall doesn't balloon out as much when the load is light and the pressure is low.
That isn't really a problem with regular inflation checks, but when failing to check pressure, an underinflated steel sidewall tire can become a serious danger to whoever attempts to reinflate the tire back up to proper pressure again.
A 225/75R16 tire is 29.4" in diameter, and rotates around 710 times per mile at 45 mph. That means the steel in the sidewall of an underinflated tire will be bent back and forth over 710 times per minute when traveling under the speed limit, and will be bent even more frequently when going faster.
If I take a metal wire coat hanger, and bend it back and forth only 10 times, the steel wire will fatigue from the flexion, and i will easily be able to sever the coat hanger in two at the point where it was bent back and forth.
The same thing is happening to an underinflated steel sidewall tire... only much faster if driven upon. The steel wires inside the sidewall are bending back and forth, to the point of fatigue. Then, when the tire is reinflated, a sudden zipper failure can occur due to the weakened steel wires. This kind of failure more often happens with 19.5, 22.5, and 24.5 tires that are all steel, as they are typically inflated to pressures higher than 80 psi.
Anyway, all this is to say that yes, there are stiffer sidewall tires out there to chose from, that are more durably constructed, as evident by the amount of raw material put into the tire itself, demonstrated by the tire's weight.
Yet that is only one parameter to consider among a host of sometimes mutually exclusive considerations... that are occluded by conclusions drawn from assumptions in the absence of enough facts.
For example, in this particular size range, many have been attracted to the relatively new European standard of tire, denoted as the 225/75R16C. The "C" in this case is not the North American designation for "load range." Rather, the C is the European designation for "Commercial", which is how Europe describes what North America denotes as "Light Truck."
The popular Michelien Agilis CrossClimate tire in this size comes in two versions... a unidirectional 225/75R16C, having a Load Index of 121/120 at 83 PSI, and an omnidirectional LT225/75R16E, that has a Load Index of 115/112 at 80 psi.
The natural assumption is that the Euro "C" version with a 121 Load Index must be a heavier, stiffer, more durable tire "commercial" tire, due to the 121 load index rating the tire at between 400 to 500 lbs. more carrying capacity than the LT LRE version of the Agilis with a load index of 115.
Yet the Euro C version of the Agilis weighs only 37.5 lbs, whereas the LT LRE version of the Agilis weighs 40 lbs. Which tire has more material?
Taking this a step further, unlike any other LT225/75R16E tire that I am aware of, and I've entered 153 different brands/models of light truck tires in just this exact size to compare, the LT LRE version of the Agilis CrossClimate is rated to 90 psi, whereas the Euro "C" version of the Agilis is max rated at 83 psi.
Note that most E-Series wheels are max rated to 80 psi, and Ford's recommended cold operating pressures on the front axle are in the range of 65 psi, so any tire pressure higher than 80 psi is purely academic. But when thinking of the strength of a tire carcass to be able to contain 90 psi, it is difficult to dismiss the Agilis LT LRE tire, which is rated to 90 psi, that also has 2.5 more lbs. of material, as being a wimpier or weaker built tire than the Euro "C" version of the Agilis. Note that the Agilis LT LRE does need to be inflated to 90 psi to achieve its load index of 115, which is satisfied at 80 psi.
The previous poster also made mention of tread depth. That is an important consideration in a steer tire. Let's compare the tread depths of just the tires discussed in this post, listed from least amount of tread depth, to most amount of tread depth, in 32nds of an inch:
11.5/32 - Michelin Agilis CrossClimate "C"
12.5/32 - Michelin Agilis CrossClimate "LT LRE"
14.0/32 - Michelin XPS Rib
14.0/32 - Bridgestone R238
17.0/32 - Goodyear Endurance RSA
There is more to compare, as mentioned by donr103... and I'm thinking of sipes in particular. Yet this post is already long in the tooth, so I'll let others pick up the torch and carry the discussion forward from here.