16 inch truck tires for the RV.

[jlarocca]

Question on this older thread, I'm going through my 2nd set of ST tires on my 2013 model camper and I'm considering going with the 14-ply tire like the Sailun or the GY G114. I'm thinking of going cheap and just buying some steel wheels to replace my Aluminum ones but was wondering how many folks out there have upgraded their tires without upgrading their wheels and if so has anyone had a wheel failure because they were running higher pressures than what is stamped on the wheel?

[CWtheMan]

Tires of all designs and sizes are built to specifications. The materials needed to attain a desired tire load capacity are part of the specifications.

Reserve load capacity is a standard term in the tire industry. It refers to a tires load capacity not used in the fitment application. When two 3420# tires serviced to their maximum inflation pressure of 80 pis are fitted to a 6000# GAWR axle and the axle is carrying an evenly loaded 6000#, each tire has 420# of load capacity in reserve.

This is how the FMVSS define the Light Truck tire; “Light truck tire means a tire designated by its manufacturer as primarily intended for use on lightweight trucks or multipurpose passenger vehicles.” ONLY it’s manufacturer can recommend the LT tire for trailer service. ONLY a vehicle manufacturer can recommend the LT tire for OE fitments on trailers.

A tire’s maximum load capacity is shown right on its sidewall.

The design of the LT tire demands more weight. it’s a mileage tire so it needs taller and more dense tread materials. Some are retreadable and regroveable. And some are completely steel cased. Some have an extra steel belt to ward off punctures and those with a commercial market will have extra materials in their sidewalls to ward off curb scrubbing damages. None of those extra add-ons add strength to a tire. They are designed for durability.

On the other hand the ST tire is designed to ward off heat. They have shallow treads and a tread pattern for that purpose. Their sidewalls are designed to flex in the lower zone for those sharp turns often required when parking. The sidewall cording is from larger diameter materials to provide the extra strength for heavier loading than like sized ST and P tires.

ST tires degrade rapidly when operated close to or right at the edge of their maximum operational parameters. As much as 1/3 in three years. So when a trailer manufacturer sets GAWR axles at 5084# and puts 2540# tires on each end of those axles, failures are not far away. Failures will even be closer if you’re operating them at or above their speed rating. Tires are designed to carry their maximum load capacity at their maximum speed rating. When being operated above that rating they degrade rapidly. Let’s say a 2540# tire that has degraded 5% is down to 2285#. Add in a 3 psi drop in recommended tire inflation pressure and its down to 2200#.


Options for RV trailer tire replacements are becoming more interesting with the speed ratings going up and being placed on the tire sidewalls for everyone to see. Any of the ST tires now having speed ratings higher than 65 MPH are redesigned tires.

The problem with RV trailer tire replacements is the vehicle manufacturer. They are very reluctant to offer any recommendations other than what was provided with the trailer or the options offered for that model year. So here is where I do make recommendations; Always check with the vehicle manufacturer for their recommendations. When making independent tire replacement selections, insure that you’re going to have a warranty. And, make sure you fill out and process the tire registration documents. Always insure that your replacement tires provide the same or more load capacity than your OE tires. I have never found anyone in the tire industry that will recommend less - on paper.

[bobbecky]

Fortunately for us, our Montana came with wheels rated 3750lbs load capacity and are rated to handle 110 psi pressure cold. The only thing we had to do was have the valve stems upgraded to all metal stems that would handle the pressure. The rubber stems that came on the wheels were maxed out at 80 psi that the GY Marathons were rated at. On the aluminum wheels, the weight and pressure is usually cast or stamped on the inboard side of the wheel.

[gearhead]

Originally Posted by jlarocca

Question on this older thread, I'm going through my 2nd set of ST tires on my 2013 model camper and I'm considering going with the 14-ply tire like the Sailun or the GY G114. I'm thinking of going cheap and just buying some steel wheels to replace my Aluminum ones but was wondering how many folks out there have upgraded their tires without upgrading their wheels and if so has anyone had a wheel failure because they were running higher pressures than what is stamped on the wheel?

I wonder the same thing. We all have our wheel/ tire issues so I will give you mine. I have 5200# axles with 6 lug hubs. My wheels are rated at 3200 if I remember right. No air pressure rating on them. They are Tredit T03 wheels. I will never exceed the 3200 pound limit on the wheels. My combined axle weight is about 8400. Since there is no air pressure limit stamped on my wheel I'm tempted to go to a 14 ply tire next time. Or maybe a load range F Carlisle.

[gearhead]

I decided to call Tredit's Texas office. I explained my issue was not a load question but purely an air pressure question. He said he had no info on pressure, just weight. He didn't sound too confident, so I asked if I could talk to someone else about it. He transferred me and I got voice mail. Well heck I got a return call 15 minutes later. The lady said the 3200# wheels are max rated at 80 and I would have issues if I put load range F or G on them. She also said not to run those higher load range tires at the lower 80psi. The side walls will flex and cause overheating. I suspected as much.