When should I replace my tires?

[OhioMark]

While I've read quite a few threads for questions and recommendations for certain brands, I wanted to start a thread on when to replace tires and what to look for regarding signs of wear.

We're going on our third year and around 7,500 on the OEM tires. No signs of tread wear and they were already rotated a couple times.

Knowing the consequences can be both dangerous and potential for damage to the trailer not to mention forced to pay "Broke down on the side of the road" prices for replacements, what does everyone recommend (signs of wear and when to change out the rubber)?

[fhenn]

Every three years when you hit the fourth year they are bombs waiting to go off unless you have LT tires.

[OhioMark]

Wow,

That is a foreboding statement.

[Dayle1]

Frank is correct. Years ago ST tires were supposed to use different rubber formulations to minimize ozone effects from sitting idle. That was so the rubber would last as long as the tread. My first set of Goodyear Marathons lasted 7 yrs and were still on the trailer when we sold it. But things have changed and even the best brands like Maxxis state ST tires should be replaced between 3 and 5 yrs and they loose load capacity with time, temperature and speed, so they can look just fine, yet fail at any time. Sometimes they explode and sometimes they begin loosing air, in which case a TPMS will help minimize damage to the trailer. Rubber valve stems should also be replaced with metal ones, some tire failures are really caused by the valve stem failing initially. Finally, inspect the tire for cracks in the rubber, especially down in the bottom of the grooves where the tread wraps around the sidewall, that is a sign the tread is about to separate from the carcass.

[r2millers]

Here's some info from Discount Tire on ST tires. They too agree with 3-5 years.


"Always inflate trailer tires to the maximum inflation indicated on the sidewall.

Trailer Tire Applications
Trailer tires are designed for use on trailer axle positions only. They are not built to handle the loads applied to, or the traction required by, drive or steering axles.
Inflation
Always inflate trailer tires to the maximum inflation indicated on the sidewall.
Check inflation when the tires are cool and have not been exposed to the sun.
If the tires are hot to the touch from operation, add three psi to the max inflation.
Underinflation is the number one cause of trailer tire failure.
Load Carrying Capacity
All tires must be identical in size for the tires to properly manage the weight of the trailer.
The combined capacity of the tires must equal or exceed the Gross Vehicle Weight (GVW) of the axle.
The combined capacity of all of the tires should exceed the loaded trailer weight by 20 percent.
If the actual weight is not available, use the trailer GVW. If a tire fails on a tandem axle trailer, you should replace both tires on that side. The remaining tire is likely to have been subjected to excessive loading.
If the tires are replaced with tires of larger diameter, the tongue height may need to be adjusted to maintain proper weight distribution.
Speed
All "ST" tires have a maximum speed rating of 65 mph.
As heat builds up, the tire's structure starts to disintegrate and weaken.
The load carrying capacity gradually decreases as the heat and stresses generated by higher speed increases.
Time
Time and the elements weaken a trailer tire.
In approximately three years, roughly one-third of the tire's strength is gone.
Three to five years is the projected life of a normal trailer tire.
It is suggested that trailer tires be replaced after three to four years of service regardless of tread depth or tire appearance.
Mileage
Trailer tires are not designed to wear out.
The life of a trailer tire is limited by time and duty cycles.
The mileage expectation of a trailer tire is 5,000 to 12,000 miles.
Why Use An "ST" Tire
"ST" tires feature materials and construction to meet the higher load requirements and demands of trailering.
The polyester cords are bigger than they would be for a comparable "P" or "LT" tire.
The steel cords have a larger diameter and greater tensile strength to meet the additional load requirements.
"ST" tire rubber compounds contain more chemicals to resist weather and ozone cracking.
Storage
The ideal storage for trailer tires is in a cool, dark garage at maximum inflation.
Use tire covers to protect the tires from direct sunlight.
Use thin plywood sections between the tire and the pavement.
For long term storage, put the trailer on blocks to take the weight off the tires. Then lower the air pressure and cover the tires to protect them from direct sunlight.
Maintenance
Clean the tires using mild soap and water.
Do not use tire-care products containing alcohol or petroleum distillates.
Inspect the tires for any cuts, snags, bulges or punctures.
Check the inflation before towing and again before the return trip.
Keys to Avoiding Trouble
Make sure your rig is equipped with the proper tires.
Maintain the tires meticulously.
Replace trailer tires every three to five years, whether they look like they're worn out or not.
Trailer Tire Warranty
The Carlisle trailer tire warranty applies to the original purchaser for three years from the date of purchase or until the tread depth reaches 3/32".
The OE (original equipment) warranty goes into effect at the time of the trailer purchase."

[rcflyer]

The most common problem I have had with ST tires and even with LT tires is tread separation.

When you rotate the tires or remove them for bearing maintenance examine them carefully.

Look for areas where the tread may appear to be more worn than the rest of the tire.

Early stages of tread separation is difficult to detect when on the trailer.

[r2millers]

On my triples, I get tire cupping due to turning and scrubbing the tires.

[ajlight]

I replaced ours after 5 years. Ours is stored inside and the tires looked good, but I did not want to press my luck. If it was stored outside I would probably replace every 3 years. UV rays are not good to rubber.
I think a lot of tire failures are from overloading and under inflated. We have been looking at different rigs and it is hard to find anything that can carry over 2000 lbs of payload. A lot of them are in the 1300 - 1500 lb range. And that is before any battery, propane or water. Probably keep what we got.

[OhioMark]

All good info. Thanks everyone!