st tires experince

[jwakeman]

I am looking at a 3721rl with factory ST tires and wondering what the real world has to say.

[Javi]

I'm guessing that you are asking about the tires and not the trailer. The condition of the tires would determine what I would do, if new I'd use them until they are two to three years old by date code. However, I am careful about inflation, loading, speed and abuse.

Bottom line is if you you lose a tire at highway speed the damage to the trailer is usually costly.

Unlike truck tires the choices for trailer tires are limited to may pop, will pop, and probably will pop. So only you can decide how long to "let her ride"

[WaltBennett]

You don't state the year or the date codes. That would help.

[JRTJH]

The "brand of trailer" or "model number" has nothing to do with how well ST tires will perform. The reputation of different brands of ST tires is probably more relevant to reliability than the brand of trailer on which they are installed. There are some ST tire brands (Maxxis and Carlisle) that have very good reputations and some that aren't so popular, typically the ones that are "standard tires" on many RV's.

Much more relevant to your concerns is how much weight is on each tire, how close that tire is to its "maximum load capacity" when operated at the recommended tire pressure, what speed you tow and the "percentage of extra load capacity" remaining when you load your RV for a trip. Also, something few people consider, is the way the tires were "treated" by the transporter while being delivered to the dealership and also how the dealer "moved the trailer around on his lot, from time to time. If the tires sat for months in an "underinflated" condition and he moved the trailer weekly with them in that condition, his actions may have a significant impact on the reliability you experience. Keep in mind that statistically, operating a trailer with a "flat tire" affects the "good tire" on that same side, probably leading to damage and destruction "down the road". How much that affects the "good tire" on your trailer, if one is "not at pressure" for months as the dealership moves it around, is something nobody has a "good handle on" as it relates to "your experiences with ST tire reliability"...

Someone else who owns the same model trailer, with tires not subjected to those conditions, will have a significant difference in tire reliability and performance. Don't forget that balancing the tires does play into "sidewall flexing" and thus "tire operating temperatures as well as physical forces which affect reliability.

Keep in mind that ST tires "lose" about 10% of their capacity every year (probably faster if you don't use your RV regularly). That means that a tire with "20% more capacity than weight carried" will be "overloaded" at the beginning of the 3rd year. That time starts with the date the tire was manufactured, not the day you buy the trailer. The tires may well be a year old on a "current year trailer" and could be 2 or more years old if you're buying a "left over model" from a previous year trailer. So the tires that "left the factory" with 20% reserve capacity may be "overloaded" due to deterioration when you first tow it off the dealer's lot.

I'd suggest you do some research on the actual size of tire on the trailers you're interested in, get their unloaded weight/tongue or pin weight, then use that "ratio" of weight carried by the pin and apply that percentage to the trailer's GVW to get the "loaded pin weight and the axle weight. Consider that amount of "carried weight" for all your tire calculations. If there's only a 10% reserve capacity at trailer GVW, you can pretty much be assured that you're "living on borrowed time" when you pull your RV out of storage for the second year of ownership.

Experiences that other people have had with their ST tires may or may not be a reliable source for what you experience based on the many variables that must be considered.

[tgpilot]

IF I recall correctly ST tires are more limited on the MAX speed limit that they can go Vs an LT tire. So, make sure you know what those max speeds are, and do not exceed them, as well as the LT tires which have a higher limit.

[CWtheMan]

IF I recall correctly ST tires are more limited on the MAX speed limit that they can go Vs an LT tire. So, make sure you know what those max speeds are, and do not exceed them, as well as the LT tires which have a higher limit.

The TRA has just recently changed the maximum speed restriction for ST tires from 65 MPH to 81 MPH. All new ST tires will have a speed letter on their sidewalls.

Before there was seldom, if ever, a speed letter on ST sidewalls. Probably because there is no speed letter for 65 MPH, so the lack of a letter indicated the tire was rated at 65 MPH.

[tgpilot]

That's good to know.

[jwakeman]

Where can I get more details about this rule change?

[TomHaycraft]

Where can I get more details about this rule change?

You beat me to the question! Trying to find it myself, doesn't look like the Tire and Rim Association (TRA) is willing to give out information for free. The "Year Book" with all specs if $119.00. Hopefully ... who was it ... CWTheMan(?), will come through with a quotable reference. For now, I'll keep my new Maxxis ST Radials at 65 mph.

[cw3jason]

There is no way I am going to run an ST tire at 80MPH regardless of what the letter code says. 65 is plenty when hauling.

[CWSWine]

There is no way I am going to run an ST tire at 80MPH regardless of what the letter code says. 65 is plenty when hauling.

X2 - While I was Germany the Germans would drive 100 mile hour to park to take nice slow stroll in the park. I'm not in that much of hurry.

[TomHaycraft]

There is no way I am going to run an ST tire at 80MPH regardless of what the letter code says. 65 is plenty when hauling.

In general, I agree, usually I'm quite comfortable at 65. However, on a stretch of road SE of Austin where the speed limit is 85, I'd like to have the confidence that nudging up to 70 or 75, won't diminish the life of my tires. With a 20+ mph speed differential, it feels like an accident waiting to happen.

[bsmith0404]

In general, I agree, usually I'm quite comfortable at 65. However, on a stretch of road SE of Austin where the speed limit is 85, I'd like to have the confidence that nudging up to 70 or 75, won't diminish the life of my tires. With a 20+ mph speed differential, it feels like an accident waiting to happen.

I've towed several trailers with tires rated for 75. There were a few times I bumped the speed up to 70 to blend in a little better with the flow of traffic. I wouldn't have done that if the tires weren't rated for it, that is also an accident waiting to happen. IMO, towing in CA is one of the worst experiences there is with a 55 mph speed limit for trucks with trailers and everyone else flying by at 70+. So I can definitely relate to your feelings.

[CaptnJohn]

Bought a new Cougar and noticed the higher speed rating BUT I'm not in a hurry to get anywhere and 60 - 65 is my comfort zone. On interstates I'm still in the right lane or rarely the middle lane. Same with distance ~~ rarely over 350 - 400 miles in a day and try to make it all during daylight. Following those self-imposed rules I'm rarely passed by a 5er or TT. During 1460 miles of my trip to/from FL I was only passed by 1 5er and 1 TT but 6 MHs and 2 of them were flying.

[SkiSmuggs]

I just feel so much more control at 60-65. But to the OP question, ST tires made in China have a dubious reputation. I had bulges appear at low mileage with maybe 3 year old tires on my previous TT. With my current 5th wheel, I replaced my TowMax china bombs with Maxxis ST tires made in Thailand and upgraded from D rated to E rated for greater load margin. I have over 15,000 miles on those with no issue, but will replace them at 5 years. I got them from Amazon and the date codes indicated they were only weeks old.

[CWtheMan]

Where can I get more details about this rule change?

The TRA is not a federal governing body. However, they do set tire industry standards which all members follow.

The new speed letter requirement is most likely a result of a customs action on imports. It is a new requirement for all ST tires from over there.