Trailer Tires

[blake in spokane]

What is the difference between ''trailer use only'' & regular car tires. This is on a single axle 20' boat trailer.

 

[gm280]

Re: Trailer Tires

WOW I've asked that same question myself a few times now. And best I can tell after reading so much about it on the trailer sites is, trailer tires are built with a stronger side-wall then normal car tires. So that helps keep your trailer from wondering all over the road. Car tires are built to allow side-wall flex so you don't have such stiff ride and better flexibility to move the car easier. So after researching it, there really is a difference between the two tire types. Even radial trailer tires are built different then radial car tires. Seems trailer tires track straighter keeping the trailer from moving all over the road while pulling it. So there is a difference for sure...

 

[kjsAZ]

Re: Trailer Tires

it depends. The major difference is that vehicle tires have to meet much tighter specs than trailer tires and that's not a good thing. That's why ST tires have the warning: not for vehicle use!
Vehicle tires have a load rating at a much lower pressure and that makes them unsuitable for most trailer applications as you have to go for a much larger tire to meet the required load spec (at a lower pressure). Most trailer tires today actually have thinner side walls than equivalent vehicle tires and the lower walking of sidewalls comes from the extreme pressure they have to be run at.
Some manufacturers actually have the same tires for vehicles and trailers and just rate them differently and those are usually the better ones. The ones I have are of that type which I found out by asking for some details. Passenger tire rated as 32PSI, trailer tire at 45PSI, same tire with different markings and naturally different load ratings. As I don't need the full load rating I run them according to what the manufacturer told me is required at my actual load.
Having said this, you have to know the load rating you need and I am pretty sure that you won't find any passenger or better LT tire which has this rating so you are stuck with a trailer tire to keep it legal. There's one thing: if you use passenger tires you have to de-rate the load rating by 10% as they also do it for mini-vans. LT tires are as marked.

 

[JimS123]

Re: Trailer Tires

When the sidewall statement says "not for passenger use" that speaks volumes. If they are that crappy that a human can't ride in a vehicle with them, then I don't want to take a chance with my fishing poles in it either.

Ever see a trailer tire blow up on the highway? Sure you have! But how many car tires explode? Sure, some do but the frequency isn't that great. The hipe about stiffer sidewalls, turning, etc is pure bull.

The bottleneck is capacity. Most car tires don't rate high enough. If your trailer has a gross load of X pounds, then the sum of your tires must exceed that. If you can get a truck or car tire that exceeds the needed capacity, I would buy that over an ST any day.

Thats my opinion and I'm sticking to it. Its based on 45 years of using car tires and never having a mishap, and 3 years of ST tires that failed, even with 100% indoor storage and full pressure.

My TeeNee came from the factory with P car tires. I guess they thought the same way. My frame covered a number of models, and the only version that came with STs were the higher rated capacity ones, where the Ps didn't provide the needed extra capacity.

 

[R DAVIS]

Re: Trailer Tires

I never cease to be amazed at the lack of knowledge some folks who give advice on these forums really have.

Here is some basic trailer tire information based on fact:

The West Advisor: Trailer Tire Basics

 

[batman99]

Re: Trailer Tires

.

I'm no expert on tires...

In reality, I do know:

If a Utility/RV/Boat Trailer has ST tires, its under 7 years old (from their build date), it blows while towing and someone gets hurt, its called an accident. Or, act of God in some insurance policies. Thus, insurance company pays.

If a Utility/RV/Boat Trailer has Passenger "P" or LT tires, its blows while towing and someone gets hurt, insurance isn't paying. And in many cases, the trailer owner will be living in a court room for the next few years (paying on their dime). And, will most likely get personally sued - for not using properly rated tires on their trailer.

For me and my many different trailers, I stick with properly rated ST tires (and under 7 years old from their build date). And, I stick with properly rated P or LT tires (and under 7 years old from their build date) under my Tow Vehicle as well. I don't purposely give an insurance company a way out - when there is an accident, someone gets hurt and someone wants to sue.

Unknown code about ALL trailers. The axle under a trailer should never be loaded over 80% of its rating. Thus, allowing 20% for sudden road bumps and double railway tracks. For example... If one's trailer is rated for 2,800 lbs (including weight of trailer), ensure it has 3,500 axle under it. And, never load more than 2,800 lbs. Thus, having a buffer. For ST trailers on my many different trailers, I do the same "next size up" as well. For example... My boat trailer came factory with ST R-13s tires. I upgraded to ST "D" 13s - which supports 400 lbs more lbs each (total of 800 lbs total). Thus, making my insurance company happy and still gaining some increased safety buffer (for those double railway tracks situations).

If one does install P or LT tires on your trailer, do get a letter from your insurance company stating this is OK (from their view). If you have a CYA letter, then go for it. Many insurance companies won't cover non-ST tires under a trailer. Mine won't (because its not minimum build spec).

This works for me...

 

[JimS123]

Re: Trailer Tires

No kidding about the "lack of knowledge". I continue to be amazed about the wrong answers given around here. What is "truth" is a grey area though. Don't believe half of what you read or "hear". Personal experience must be the guide.

As far as the legality or insurance coverage of P or LT tires on a trailer....never heard of that before. Sure would like to see a government or lega link in that regard.....LOL.

The 7 year reference is also a bit spooky. It should be common knowledge that an ST won't last nearly that long.

The "West Advisor" is a perfect example to back up my case. Obviously, the car tires are stronger, thus no reason to not use them. My second backup is (as I already stated) that some trailer manufacturers use P tires, provided that the capacity meets the specific trailer's requirements. That fact in itself would limit the liability of the purchaser if those tires came that way from the factory.

 

[batman99]

Re: Trailer Tires

.... As far as the legality or insurance coverage of P or LT tires on a trailer....never heard of that before. Sure would like to see a government or lega link in that regard.....LOL. ....

Don't need to provide a URL. Please write your trailer insurance company and simply ask them that if one installs LT or P tires on one's "trailer", its tire blows and because of this tire blowing out, it hurts someone, will they cover the liability because of it? Simple question for your insurance company. I don't need to provide a URL. Just like I don't need to show a URL that my insurance company won't cover a law suit if I was driving drunk, got into an accident and hurt someone. For non trailer tires on a Trailer, simply write your insurance company and see what they reply back in writing...

 

[lrak]

Re: Trailer Tires

Don't need to provide a URL. Please write your trailer insurance company and simply ask them that if one installs LT or P tires on one's "trailer", its tire blows and because of this tire blowing out, it hurts someone, will they cover the liability because of it? Simple question for your insurance company. I don't need to provide a URL. Just like I don't need to show a URL that my insurance company won't cover a law suit if I was driving drunk, got into an accident and hurt someone. For non trailer tires on a Trailer, simply write your insurance company and see what they reply back in writing...

Mine will in both cases. Can we see the reply from your insurance co?

 

[MH Hawker]

Re: Trailer Tires

I find it a lot simpler to use what ever fits the application and go boating.

 

[R DAVIS]

Re: Trailer Tires

Don't need to provide a URL. Please write your trailer insurance company and simply ask them that if one installs LT or P tires on one's "trailer", its tire blows and because of this tire blowing out, it hurts someone, will they cover the liability because of it? Simple question for your insurance company. I don't need to provide a URL. Just like I don't need to show a URL that my insurance company won't cover a law suit if I was driving drunk, got into an accident and hurt someone. For non trailer tires on a Trailer, simply write your insurance company and see what they reply back in writing...

Batman has NO IDEA what he is talking about.

I am a retired Regional Claim Manager for a large insurance company. I am still amazed every time I see someone with so little knowledge of a subject make such a feeble argument. And, YES if you are driving drunk and cause an accident, your insurance company WILL pay liability damages as well as damage to your vehicle (if you have collision coverage).

This is the kind of ignorant misinformation that gives the insurance industry a bad reputation.
Note: I do not mean any personal disrespect, but only criticize his POST and his lack of knowledge.

 

[JimS123]

Re: Trailer Tires

I find it a lot simpler to use what ever fits the application and go boating.

As I said earlier, my tandem boat trailer was equipped with P tires from the factory, and that's what was listed in the specs in the manufacturer's catalog.

The key is the load rating. Divide your requirement by the (number of tires times the individual load rating of each tire). If that exceeds 1 you're good to go as long as you run max pressure in the tires.

Personally, I'll take the tire with heavier sidewalls and a stronger build any day. The only STs I run in my 4 trailers are ones where I can't get a P or LT that has a high enough load rating.

 

[kjsAZ]

Re: Trailer Tires

.
If a Utility/RV/Boat Trailer has ST tires, its under 7 years old (from their build date), it blows while towing and someone gets hurt, its called an accident. Or, act of God in some insurance policies. Thus, insurance company pays.

If a Utility/RV/Boat Trailer has Passenger "P" or LT tires, its blows while towing and someone gets hurt, insurance isn't paying. And in many cases, the trailer owner will be living in a court room for the next few years (paying on their dime). And, will most likely get personally sued - for not using properly rated tires on their trailer.

Absolute and completely wrong! As some said, tons of "found on the internet so it can't be wrong". If the load rating was sufficient there will be absolutely no difference. Insurance pays. Oh, and you can be sued in both cases.....

Contact some tire manufacturers and not the ones who only import crap from China and if you find someone who is talking you will find out the real truth. ST tires are mostly the bottom end of the food chain. That West Advisor link is just a re-spin of some marketing speech they found somewhere too like most of their so called advise.

 

[oldjeep]

Re: Trailer Tires

FWIW, pretty much all light duty car trailers (6-7K) I've ever seen or bought come with either P or LT tires on them The need for ST tires is in the smaller sizes where you can't get a non ST tire in that size that has the same load capacity.

 

[oldjeep]

Re: Trailer Tires

Don't need to provide a URL. Please write your trailer insurance company and simply ask them that if one installs LT or P tires on one's "trailer", its tire blows and because of this tire blowing out, it hurts someone, will they cover the liability because of it? Simple question for your insurance company. I don't need to provide a URL. Just like I don't need to show a URL that my insurance company won't cover a law suit if I was driving drunk, got into an accident and hurt someone. For non trailer tires on a Trailer, simply write your insurance company and see what they reply back in writing...

FWIW - if you are driving drunk, your insurance co will cover you. They will drop you immediately after, but that is what insurance is for.

 

[kjsAZ]

Re: Trailer Tires

FWIW, pretty much all light duty car trailers (6-7K) I've ever seen or bought come with either P or LT tires on them The need for ST tires is in the smaller sizes where you can't get a non ST tire in that size that has the same load capacity.

absolutely correct! ST tires get their higher load rating by increased pressure and nothing more (and less stringent specs). They are a US and Canada specialty and probably some neighboring countries.

 

[bruceb58]

Re: Trailer Tires

If you want to use P size tires you need to derate the load capacity by 10% for trailer use. In many use cases, that will be pretty much impossible if you are running 14" tires and a heavy load.

I only use ST tires myself. The stiffer sidewall to me is an important difference.

ST tires get their higher load rating by increased pressure and nothing more

Please post a link to info that supports this statement.

 

[oldjeep]

Re: Trailer Tires

If you want to use P size tires you need to derate the load capacity by 10% for trailer use. In many use cases, that will be pretty much impossible if you are running 14" tires and a heavy load.

I only use ST tires myself. The stiffer sidewall to me is an important difference.

And I don't think you see too many folks using P tires on 14" trailer wheels. You can get a few LT tires in those sizes but they cost so much that it isn't worth the trouble. My boat trailer is one of those that runs a god awful size/load combo that I can only order online. (185/80-13 D rated tires) I wish that there was a more available car/truck alternative for those.

My current car trailer runs E rated LT tires, which are as stiff as any trailer tire you are going to find - but easier/cheaper to get ahold of when you need one.