Trailer tires - I don't get it.

[Marco Flamingo]

While looking at information on trailer brakes, I came across a lot of discussions where people experienced a tire blowout on a trailer. A recent post here ("Florida Trip") just mentioned two blowouts in a single trip, maybe even a single day.

I read that one should use tires labeled ST (for Special Trailer) as they have stiffer sidewalls and can carry more load, but then I see all the threads about blowouts. I've never had an actual blowout with regular street tires. I had some tread come loose back when all I could afford was re-treadded tires (which we referred to as "May Pops" even though I never had one pop".

I'm now looking at the possibility of larger wheels as part of my adding trailer brakes and maybe getting rid of my 175/70R13 wheels. It turns out that I could fit a 175/70R14 or 15" wheel and tire. These were used on many sports cars in the 1060-70s and are still fairly common. It's basically the same tire as was original on my 1973 Volvo. The modern version of that tire has a weight rating of over 1,100 pounds, which is plenty for my boat and trailer.

Is there really a reason to stay with a 13" trailer tire over a 15" passenger tire?

Mark

[Dora~Jean]

Yes, easier to float your boat when unloading/loading at a ramp.

[SVal]

Well, my two bits. I have had a towing/transport business for many years and...
I have responded to many accidents caused by trailer tire failure. Most often it is
#1 an under-inflated tire (should be inflated to the manufacturers rating, these are computer generated ratings not the old day bias tires)
#2 failure to use a non trailer rated tire.
I appreciate the work as does the local hospital.
Steve

[hardee]

Yes and Yes.

There are reasons to keep the 13 and reasons to go with a 14 or 15.

To keep the 13. It gives you a lower or shallower launch platform. It is easier to maneuver if you are ever hand pushing the trailer around by hand. Lower platform means you can get it in under a lower garage door opening.

AND....

It go to a larger diameter (14 or 15) tire. That will give you a higher axle clearance, should you run across (straddle) any road hazard (sometimes called Ally Gators -- pieces of tire or retread on the highway). The larger tire diameter will give a higher launch platform, by maybe an inch, but will give a bit smoother ride. The larger tire will also make few revolutions per mile, so will maybe last you longer between changes. They will also be slightly harder to muscle around if you are hand pushing. The larger tire will probably give you a higher load range rating, which you might be able to run at a slightly lower inflation pressure (be sure and check that with your dealer) but as long as it carries your load, it may be softer riding.

If it was me, I would be going with the 15 if it would fit. It will make such a small difference in your launch depth you will hardly notice. Going around the circle less often it may run just a bit cooler, less likely to blow. JMHO.

Harvey
SleepyC

[Jake]

[Will-C]

I would not think that for a 16' boat you really need to go with larger wheels and tires unless you are going to be doing a lot of high speed highway type trailering. A previous boat, a 19' center console which was on a single axle trailer rated for 3900 pounds came with some crappy tires called Planet something. They wore out in three thousand miles with proper inflation and they wore in a very lumpy fashion. Since I normally trailered the boat about two hours to the New Jersey shore with not a lot of speeds over 55 I could not believe it. The dealer was kind of o well about the tire situation. I put a set of Michelin E rated radial tires and never had a problem. I'm not recommending for anyone else to go this route but I think the trailer tires being offered these days leave a lot to be desired to put it mildly. I'm a firm believer in radials and have tires and wheels balanced. I pay particular attention to not pull the tires over curbs which can bend wheels and a damage the tire. I would have put Michelin radials on our last boat but I could not find them in a 14" size. Our new boat which is on a 12,000 pound rated tandem axle Float On trailer will get Michelin radials if the factory supplied radials can't cut it. I think if the tire decent quality tire that is rated for carrying a given weight. As stated here I think trailer tires over four or five years old ought to be replaced if you going to run them on extended trips at highway speeds. I have pulled a lot of different trailers over my 67 years. I find it funny that on tractor trailers you can run the same type tires on the tractor that you run on the trailer. All this is just me but I don't really think tires with ST ratings are not all that special.
D.D.

[JamesTXSD]

Trailer tires lead a tough life - carrying a heavy load, lots of sitting, twisting turns, etc. You really do need the tougher sidewalls of the ST tires.

Years ago I read that for every inch higher on the trailer, you have to go another foot further in the water on the slop of a typical ramp. I can't verify that, but extra height does make a difference. That said, I would prefer the highest load rating I can get on a trailer tire.

Another thing some folks are not aware of: trailer tires generally have a speed rating well below that of passenger car tires (frequently 65 mph). We have all seen a trailer that has a small bit of sway going down the road - that puts additional side loads, generating more heat.

We have had a blow out on a boat trailer and on a 5th wheel trailer. Both had tires that were less than 4 years old. Both had tires that were properly inflated. Both had plenty of tread left on the tires. In each case, the road service guys that came out said they recommend changing trailer tires every 3 to 4 years, preferably 3; and that trailer tires are not made as well as they used to be (seems that all are made in China these days). Both said, in their experience, that trailer tires come apart before the tread is worn out, unless the axles aren't aligned. I used to run Goodyear Marathons and went to Carlisle ST on the recommendation of tire shops.

That is an expensive load riding on top of the tires - it isn't a place to scrimp, even if you are thinking you aren't going to be putting a lot of miles on them.

We check the air in trailer tires regularly while towing, and I put an infrared thermometer on them, as well as on the hubs at each stop.

[Marco Flamingo]

Thanks for the responses. One of the reasons I was thinking of bigger wheels was because I hope to do a lot of long distance towing. Speedometer tables show that a 13" wheel at 65 mph spins the same as a 14" at 63 mph or a 15" at 60 mph. Not a huge difference, but some. And a larger diameter tire rides smoother on a passenger vehicle. Not sure that it matters too much on the trailer.

I had forgotten about height. It sure was nice to be able to put my 16 in the garage this winter for all the repair work. I think that I have two inched to spare, but I'll be sure and check before I make any changes. Being able to garage the boat, even temporarily, is not something that I want to give up. I could let the air out of the tires when putting it in, so I think there are work-arounds.

My trailer has Goodyear Marathons with a C load rating (1,360# each). I haven't located the date code yet. They still have the little "new tire" nubbies on them, but I know that doesn't mean that they are new. The prior owner lived in Campell River and kept the boat on a trailer about 300 yards from the launch ramp. They might be 2005 tires with 10 miles on them.

From what I've read online, it isn't the date on the Marathons that is most important, it's the manufacturing facility. Goodyear switched to a Chinese manufacturer for its Marathons and the claims are that the tires are no longer top-of-the-line.

I still haven't seen any convincing evidence or arguments for using only trailer tires on a small trailer. In fact, the argument for passenger tires is fairly compelling (ignoring for a moment the "if you don't use trailer tires you will die" type of argument). First, trailer tires are rated at 65 mph maximum. Above that, they tend to generate too much heat, leading to failure. I know that I'm the only one who has ever exceeded 65 mph, so looking for a higher speed rating may only apply to me. But why would a passenger tire, rated at 120 mph and carrying well under it's load rating, fail at 70 mph? Can it sense that it is on a trailer rather than a car?

Second, with the CD 16 it is easy to get over the trailer's load limit with 14 and 15" passenger tires, so no need for special trailer tires based on weight carrying requirements. Popular street tires would be load rated at 2,300# on my 2,000# trailer (that weighs 1,750 when loaded). I could get D or E rated trailer tires which would work out to over 3,000# carrying capacity, but it is still only a 2K# trailer. Sometimes more is better. Sometimes more is just more. I can't think why more weight capacity would be better in this case.

Third, (I haven't confirmed this yet but I read it on the interweb so it must be true) the acceptable failure rate is different. Passenger tires must meet a higher standard. It makes some sense that a tire used on a vehicle travelling +80 mph and containing passengers would be held to a different standard than an unoccupied trailer travelling at 60 mph. And have you ever heard that you should change your passenger tires every 3-5 years regardless of mileage? What would you think of your car tires if you were told to change them every three years? Makes me think that there might be different manufacturing standards.

Even the "stiffer sidewall" claim of the trailer tire seems odd. Several places on the web (who sell trailer tires) state that radial trailer tires are better than bias trailer tires because they have a more flexible sidewall and give a better ride for easier towing. This tire is too stiff. This isn't stiff enough. This one is just right. It sounds a little bit like Goldilocks shopping for tires. It makes me wonder how much of what is "known" about trailer tires is a fairy tale.

Time for more research.

Mark

[thataway]

Mark, how much are you going to be trailering?l If it is long distances then 14" tires. If you want the brakes, because of a marginal braking system in the care--then add the brakes. Even with 14" tires there may be more clearance problems. The diameter is of the RIM, not the outer tire. The distance off the ground for a 15" tire is likely going to be substantially more than the 2" difference in diameter (theoretically it would only be 1" --half the diameter, since the axel is at the center of the hub/wheel. Tires have different thickness.

For short distances and low speeds stick with the 13" tires--if you must have the brakes, then don't go up any more than you have to in size. The 13" tire is going to be rated at lower speeds than a 14" tire, because of the increased revolutions.

Yes, radial car tires can be used on trailers. The side walls are only part of the capacity rating--and the stiffer side wall has more to do with turns, scuffing, and less sway--they don't have to flex like a passenger car. Often passenger car tires are derated by 10% of rated capacity when used on a trailer.

There have been negative reviews on almost every brand of trailer tire. Marathons used to be great--more recently there have been negative reviews. Carlisle, was good, then bad, and more recently rated good again. I think it is sort of a crap shoot, since most if not all trailer tires are made in China.

[Dreamer]

Here's a 16" Load range E Goodyear Marathon:


I replaced all four with Michelin XPS Ribs, LT rated with a steel belt in the sidewall. At least Goodyear paid $1300 for the tire, service call and body damage to my trailer!

I'll pass on ST Rated tires, especially those made in China. The testing requirements for ST rated tires is far less stringent than for LT Rated tires.

[Sunbeam]

My 22 sits on a tandem trailer with 13" wheels/tires. It tows beautifully, and I've gone cross country (and "up and down country") several times. Tires and bearings run cool, trailer has no bad habits. BUT, I have considered going to 14" tires for a couple of reasons, both having to do with tire selection (when purchasing).

1) I've only found one brand of 13" trailer tire in my size that is a Load Range D. I can run Load Range C tires, but they are getting up toward their maximum. That is, they are under maximum but not by a huge margin. Even though I can get the one brand of tire in Load Range D, it bugs me to only have the one choice, and it's a challenge to find them with date codes less than a year old.

2) Even in a Load Range C, there isn't that great a selection. For example, I have read many good things about Maxxis trailer tires, but they are not available in my 13" size. With 14" tires I'd have better selection.

Alas, there'd be a fair amount of work for me to run 14" tires on my trailer. Frame-wise no problem, as the same trailer frame was offered in either 13" or 14" tires; but it would require whole new "sleds" (the way the trailer is designed, the springs and various other parts of the way the wheels/fenders/etc. mount are one big sliding undercarriage of sorts, and I'd have to replace the whole thing). Since my trailer works fine as is, I am not motivated enough to make the change. However if I were designing from scratch, these factors would lead me to use 14" wheels. My boat does ride low, so I guess it is an advantage for launching/retrieving; but not sure how much difference a 1" larger rim would make.

[Sunbeam]

PS: Meant to add that I don't know about running non "ST" tires on a trailer which is why I didn't address it. I've only read the standard reasons why to run ST tires and that's what I do. I hear your question though!

[Marco Flamingo]

Sunbeam,

You must have an EZ Loader. I bought Tie Down stainless brakes instead of Kodiak because they will fit a 13" wheel. They are 9 .5 inch discs instead of 10. That way I can keep my 13's and and all of the axle fittings and hopefully get everything to fit under my stock EZ Loader fenders. I can then see where I am as to whether 14 inch wheels can be fitted. There are lots of tire size calculators on the web that give diameter and thickness of various tires to the 10th of an inch.

Dreamer,

I took a similar tire in to Les Schwab off of my wife's Prius. She said that the low air light came on, but she was late for the ferry and drove for another mile. Bad choice, but Les Schwab said that it was covered by their warranty and put a new one ($155) for free. They always get my business.

My theory is that trailer tires look like "blowouts" more often than passenger tires because the normal warning signs aren't felt by the driver until it's too late. It might only take a quarter of a mile, which is only 15 seconds at 60 mph, to go from really low to really blow. That's barely enough time to say "Hey, what the . . .?" Pictures like yours spook me.

I am thinking about trying some long distance trailering. It's 692 miles from Seattle to Bella Coola. That's on my to do list. 1,122 to Prince Rupert. 1,982 to Loreto. I can't find the mileage to Lago Titicaca. Probably just as well.

Mark

[Wefings]

Roger nailed it . LT rated tires are what go on my transport trailers, if there is an appropriate size available . It they are good enough to carry human lives and the weight of fully loaded trucks , they are good enough for your boat .
Marc

[hardee]

I'm with Roger (Dreamer) on this one. My next trailer tires are going to be truck tires. AND since I have had such good service from Les Schwab for 30+ years, they will most likely be LS LT tires.

Pressure checks and temp checks are regular when towing.

Harvey
SleepyC