Trailer Tires --- Any ST tires rated for more than 65 mph?

We have been reading tire blow-out horror stories as we wait to pick up our new Casita 17' trailer.  (Thank God we were ignorant when we did our 9-month cross-country trip a few years ago in a used ultra-light travel trailer --- we would never have left home if we had known then what we've learned in the past few weeks.)

So... we were, and will continue to be, meticulous about checking the cold psi and inflating if needed.  We will check the tire condition at every stop, before we pull out.  We promise to cover the tires.  HOWEVER... the Marathon tires that come with the trailer are rated for only 65 mph.  That means we'll be keeping to 55 mph.  We would like to go somewhat faster, when conditions allow it, in the states that permit it.

Our question: are there any high quality, 14.5 to 15" trailer tires (i.e., ST tires) that are rated for a higher speed?  Maybe 75 mph?  With a max of 75 mph, we could travel at 60 to 65 mph on smooth, flat stretches of lonely roads.

With thanks in advance for any input,

E. Graham

E. Graham,

I've never owned a trailer. That being said, I don't think you have to use ST tires. I think you can use LT (light truck) tires. Maybe you could find what you need in a LT tire.

If the tires are rated for 65mph, why are you concerned about running them at that speed?  Just don't exceed it for more than brief periods, like passing.  Get a tire pressure monitoring system, like the Pressure Pro, and you can monitor the tire pressures from your tow vehicle.

Don't waste your time and money with tire covers.  They won't do a thing for tire life, and may actually be detrimental due to heat buildup.

Ned said:

If the tires are rated for 65mph, why are you concerned about running them at that speed?  Just don't exceed it for more than brief periods, like passing.  Get a tire pressure monitoring system, like the Pressure Pro, and you can monitor the tire pressures from your tow vehicle.

Don't waste your time and money with tire covers.  They won't do a thing for tire life, and may actually be detrimental due to heat buildup.

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Excellent advise Ned.  My nephew has been in the tire business for years and ha has often told me that tire covers  really help his business.

I too wonder why the OP is worried about tires that are rated faster than 65MPH, in most states that is over the speed limit for vehicles pulling trailers.. Oh, I know you see them wizz by at 80 or even 90 but the fastest truck speed I encountered yesterday was 60.. The fastest speed I drove was also 60,  I mean, the RV life is all about taking the time to stop and smell the roses... Not speeding and landing in thorns.

Gentlemen,

Thank you for your input.  We don't travel at more than 55 mph when we're pulling the trailer (leaving a small margin for safety).  We are not speed demons.  As I said, however, when conditions warrant it (straight, lonely, BORING stretch of highway) and state laws permit it, we would sometimes like to go faster than 55 mph and stay within 80% of the tire's rating for speed.

However, in my reading about tires I've come to understand that exceeding 65 mph on an ST tire --- even only for a few minutes every so often (to pass, for example) --- has two major effects:  it violates my insurance and it puts the tires under stresses for which they were not designed.  Therefore, I'd like to mount tires that are rated for higher speed, to increase the margin of safety.

Alaskasnowbirds suggests LT tires.  Are there any downsides to mounting LT tires on a trailer?

Again, thanks to you all for your helpful responses!

E. Graham

The Rubber Manufacuturers Association (RMA) sets the standards for tires that are then adhered to by manufacturers. If they have set 65 for ST tires than its unlikely you will find anyone producing a higher rating. As to LT in place of ST I think this writeup might help


http://www.taskmasterproducts.com/acatalog/whybuytrailertires.pdf

You can use any tire that has a load rating sufficient for your trailer weight (axle weight for 2-3 axle models). LT (light truck) tires work well because they have  come in higher load ratings than P (passenger car) tires, but that is not likely to be a concern on your Casita. Nor would I expect the sidewall flex mentioned in the excellent article that blueblood referenced to be a concern on your relatively light trailer.

But you are being unnecessarily conservative in staying at 80% of the rated speed. What you do need to watch carefully is tire inflation, which should be correct for the actual loaded weight of your trailer - or maybe even 5-10 psi higher.

Great article!

This is such a GREAT forum.

Thank you,
Elisabeth

Elizabeth,
The speed rating is for maximum sustained speed; not the occasional downhill run or passing. You needn't be concerned except if you run for long periods in excess of that rating, or are overloaded, or under-inflated.

Karl,

That's really helpful.  Thanks.

And I seriously love your tag line. 

Elisabeth

Use LT tires....that's what I have on mine.

Reviving an old thread, simply in an effort to keep the info together.  Good article on ST tires, BTW.

We are changing our TT tires from stock to E rated truck tires: 

Loadstar K550, ST205 75D14, 1760# @ 50psi Max
to:
Michelin LTX, 215/85R16E, 2680 @ 80psi

The reasons are:

1) Helps to raise trailer, contributing to it being parallel to the ground as we have a high profile TV.  We also are on back roads occasionally and the current departure angles are way low for this kind of activity.  I've already scraped just getting in and out of some RV park entrances.  As many are aware, not all RV entry/exits and roads are created equal.   As well, BLM and Forest Service roads are, well, you never really know.

2) We drive faster than 65mph, the speed rating limit of these tires.  If for no other reason, the truck will do 75mph easily and I do NOT want to be a roadblock in heavy traffic.  While 65 is a comfortable speed for us, I prefer to travel with the flow of traffic and that means up to ~75mph where legal. 

3) The ST tire ratings and bias ply don't impress me as having any margin of safety with a trailer that is just short of 6500# loaded. (1760#x4=7040#)  Yes, the axles are only rated for 3500#/axle, but previous experience with heavily loaded utility trailers with #84 spindles suggests this will not be an issue as long as the bearings are serviced correctly. 

4) Yes, the TT has room for the tires, particularly so after putting the axles under the springs rather than the stock position of over (between spring and frame).  The axle reposition was required to get the stinkin thing level with the high 4x4 profile, even with a long drop shank.  I'm also going from 4 leaf to 5 leaf springs to aid stability.

5) I'm not willing to bet the safety of my family and my TT investment on the bias ply ST tires.  Especially since we do travel in the Western US during the blistering HEAT of the summer.  This heat has contributed to killing more than one tire for us over the years.

Negatives:

1) The larger tire diameter will have a negative impact on braking force, but I've never had to use them full tilt even in an E-stop.  The 1-ton w/exhaust brake contributes significantly to good braking quality.  If it has too much of an negative effect, I'll just upgrade to axles with 12inch brakes rather than 10inch.

2) Higher center of gravity.  No getting around this.  Just have to be aware of this fact.  Going from 4 to 5 leaves will help.  The E rated tires are also pretty darn stiff, making up some lost ground.

Does anyone see anything in err here?  Opinions, suggestions?  What have I missed?

Nope, no errors  I can see. I think LT tires are a better choice than ST any day.

Are there any LT tires that someone would recommend?  I'd like to replace the marathons on the trailer we have since they are starting to show some cracking on the tread.  We bought it used, so I'm not sure what their history is.  I have replaced one of the tires about a month ago due to some sidewall bulge and noticable sidewall cracks and when the shop was removing it, I saw there was a white wall on the inside of the tire, so it must have been a passenger tire.

I purchased a towmax brand tire, mostly out of need since we were taking the trailer that weekend and I didn't feel safe with that bad tire on it, but I would be up for some decent LT's if anyone has a suggestion.  The tire size is 205/75/15 if that matters.

Shawn,

I'm no eggspurt , but I would first suggest looking at the GVW rating of your trailer, dividing that by the number of tires and starting there.  It would be helpful to know the actual loaded weight as well, just to be sure you're on the right path.  Make every effort to go above that computed value.

I tend to err on 'heavier' than necessary for most everything and especially tires since they are a critical component.  The risk is just too great, IMHO.  As well, I have factored in the hot temps of the Western states and gravel roads (brutal on tires), which are not uncommon in the Western states.

As far as brands or a specific recommendation?  The old adage, 'You get what you pay for' is quite true with tires, so get the most you can afford that fits with your risk profile.  For example, Michelins are expensive, even 25% more, but my personal experience with them has been Top Drawer.  To me, they are worth it.  Do I buy other brands?  Yes, different applications and offerings dictate other choices.

You'll also note that I am making the jump from 14" rims to NEW heavy duty 16" rims to open up the number and type of tires available.  Anything over a C load rating for an LT tire are few and far between with 15" tire/rim combination.  Go to some of the manufacturer websites and look at their offering charts for 15 and 16 truck tires and you'll see what I mean.

Unless specifically made for heavy duty use, 15" rims don't have the section thicknesses necessary to take advantage of higher load rated tires and their corresponding pressures.  Check your rim rating.  It is usually stamped on the inside of the rim.

1) The larger tire diameter will have a negative impact on braking force, but I've never had to use them full tilt even in an E-stop.  The 1-ton w/exhaust brake contributes significantly to good braking quality.  If it has too much of an negative effect, I'll just upgrade to axles with 12inch brakes rather than 10inch.

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Nothing in error, but a suggestion. If you've ever had to make a full panic mode stop and all four wheels did NOT lock up, you already need larger or better brakes, or they need a serious rebuild. The point of highest adhesion occurs at the exact moment of lockup, so it appears your brakes are not giving you maximum braking capability. Personally, I'd go with the 12" brakes right away and have it over and done with.

You may want to look at the Hankook Dynapro listed here. I replaced my old Michelins with these and couldn't be happier. Don't let the $90 price fool you - these are quality tires!

Quote
1) The larger tire diameter will have a negative impact on braking force, but I've never had to use them full tilt even in an E-stop.  The 1-ton w/exhaust brake contributes significantly to good braking quality.  If it has too much of an negative effect, I'll just upgrade to axles with 12inch brakes rather than 10inch.
Nothing in error, but a suggestion. If you've ever had to make a full panic mode stop and all four wheels did NOT lock up, you already need larger or better brakes, or they need a serious rebuild. The point of highest adhesion occurs at the exact moment of lockup, so it appears your brakes are not giving you maximum braking capability. Personally, I'd go with the 12" brakes right away and have it over and done with.

Click to expand...

Thanks Karl, I needed that for an excuse to do what I would prefer to do anyway.   If this method doesn't work, I'm only out the hub/drum assemblies and those can be sold...

Seriously, I usually only have the controller set .4 or .5 out of 1.  Once I get this project done, I'll set it on 1 or full energize and see how she does at highway speeds.  That will be the test.  If braking performance doesn't get at least a chirp, those new axles go on the order list. 

Disclaimer: Be VERY careful doing full on brake tests.  If you don't feel comfortable doing it, get an experienced driver to do it for you.  Dry pavement only, empty, smooth back highway, maximum attention.  If things don't go as planned, it can get harry fast.  Start with low speeds and work up.

Had a tire failure the other day. Tire exploded and did damage to wheel well and side skirt. Looked like a sidewall failure. Tires were Goodyear Wrangler HT LT235/85R16 Load Range E. When I bought my present 5er in Mar 05, I checked the DOT dates on the tires and insisted on a brand new set so all tires were built in 1st qtr of 05. I'm a fanatic about pressure and keep the tires at 80 psi cold per the Alpenlite specs. I have weighed the trailer and am well below the weight limits. Last year I was leaving Disneyworld in Jun and noticed a huge bubble on one of the tire sidewalls. Went to CW, replaced the tire and had all the others closely checked for cracks and rot. Now another one went bad (on the same side, maybe a coincidence). Needless to say, I'm not to high on Goodyear right now. Looked up the Hankook and they appear to be Chinese...no thank you very much. Haven't heard too much good lately about Michelin either. But I am going to get a new set, just don't know which brand to zero in on.

I don't have a tire monitor system but the failure came so quick, I doubt I would have had advance warning. Maybe a tire temperature system may have helped, no way to tell. Think I'll start using my IR temp guage at each stop to check tire temps...may be able to spot one running hotter than the others.

Strange, Bruce. I've heard some complaints about the Goodyear Marathon trailer tires, but never the LTs. I've run them on several SUVs with no problem, but trailers sure seem to have a way of bringing out the hidden flaw in a tire!

Bridgestone/Firestone, Goodrich, Cooper and Kelly make LT tires, to name a few.