Kumho blowout!

[ShrimpBurrito]

I had a blowout on a Kumho Radial 857 trailer tire today. I believe I have the honor of being the first on this forum to do so, so I sort of feel honored. The details:

blowout occurred 80 miles into the trip today
I had checked tire pressure before leaving, and confirmed it to be around 63 psi. According to Kumho, that should have given me a load rating of 2146 lbs per tire, or ~4,300 lbs total. I haven't weighed my TM yet, but given a generous gross weight of 4,000 lbs and a conservative tongue weight of 600 lbs, that would mean only ~1,700 lbs on each tire, well within the rated range.
We were loaded as we always do for thousands of miles and probably 30-40 trips -- toilet charged, fresh water tank and hot water heater full, and a 3 drawers of clothes. Fridge was stocked, but that's about it. The cabinet under the rear bed is mostly empty, I have 2 T-105 batteries, pots and pans, and 3 camp chairs.
the tires were 3.5 years old based on date of manufacture. They had been in service for 3 years, and had been used regularly, on average once a month, but a few times (maybe 3) they had gone without being moved for 3 months.
I was going 60 MPH
It was about 65 degrees at our house when I left; within 1 hour into the trip, it was 98 degrees outside, so we had been running in that temp for around 1.5 hrs
It happened on the passenger side, so my new shield around the plumbing that I installed THE DAY BEFORE YESTERDAY wasn't tested.
This blowout happened on the same side as our first blowout with a Marathon, which presumably has a lighter load than the driver side due to no water.
I had just repacked the bearings about 6 weeks ago. We did a 15-hour roundtrip drive immediately thereafter in 70 degree temps, and the hubs were lukewarm at best; definitely no where near hot.
Both tires, wheels, and hubs were very warm. I could grab hold of the hub for a good 30 seconds before it starting getting uncomfortable.
It appears the tread separated, but there is what appears to be a transverse tear across the tread. I'm not sure if that is a cause or effect.
my custom made replacement wheel well (with no wheel well modification done) worked like a champ. 14 or 16 gauge (I can't remember) galvanized steel, welded at all seams. Zero damage, and barely even a scratch to the well.
I looked for any physical signs of foreign objects that would have contributed to failure, but didn't see anything.


Amazingly, between changing the tire myself and getting the spare replaced 5 minutes down the road, we were only delayed 90 minutes. But unfortunately, I think, they did not have any Kumhos. So I ended up getting a Maxxis 205 75/R14, but it's max load capacity is only ~1750-1800 lbs at max psi. Plus, it's a slightly smaller tire than the Kumho -- probably an inch smaller in diameter -- so if I ever have to mount it, I'll be towing with 2 slightly different sized tires. Probably not a huge deal, as the doughnut spare tires are way smaller than regular car tires, and you can get around just fine.

I'm not sure what to do at this point. I concede that the tires are getting up there in age, but I didn't think I was at the point of risking failure. So what was the problem? And what should I do? My options as I see:

keep going with existing setup, with two 3.5 year old Kumhos and one lesser load rated Maxxis -- we have 7,500 miles left on this trip.
dump the Kumhos and get 2 new Maxxis tires to match the spare, although this puts the load rating back down to what the Marathons were.
chalk it up to age, and buy 3 new Kumhos, and try to sell the spare back to whatever deal I buy them from.

I should note that I will be at the TM factory next week, but that's a few thousand more miles down the road. I'm not sure what my options are in upgrading to 15" wheels. I have the older style wheel wells, and I am very close (maybe 1" IIRC) from the frame cross member in back of the wheel. My TM tracks very slightly to the right due to the factory welding the axle about an inch or so (IIRC) further back on one side vs. the other. Could that contribute to failure, or would that just result in uneven wear, similar to a car out of alignment?

What would you all do? We continued on for another few hundred miles, where the temp ranged from the mid 90's to the low 100's. We're just outside of Vegas tonight, and we're headed to Utah tomorrow, where it is supposed to be just as hot.

This is very, very frustrating.

Dave

[B_and_D]

I'm not sure about going to the 15" wheels at this point in your trip, but I would definitely get a matched new set of tires. You could always keep the Maxxis as a "spare" spare, in case you have another blowout, and can't find a tire to match the others. You could order one to match at that point and pick it up along your way.

Sorry to hear this, I hope the rest of your trip goes blowout free!

[Joseph]

First thank you for all the information and the pictures!

Boy does that look familiar...

FYIW there are some nuances with the trailer that may have contributed along with temperature and weight and tire age but I am not saying any of those single factors caused the blowout. Even combined it does not seem like enough. If that were so I would be expecting the other tire to pop as well. Like on the same trip, same day, as has been stated in other posts. From reading your many past posts I can tell you take good care of your TM. I do not think it is anything you could have avoided. From looking at the pictures, and this is a guess, looks like the tires working environment that day and age may have been getting close to the limit and that particular tire hit something to weaken it where the transverse tear is. A deep, wide crack in the road maybe? Maybe not even hit on that day? I have heard that sometimes a tire can take a hit and keep going for a while before the damage shows.

As for what to do...:rolleyes: If it were me. . . get another class D tire on that spare asap to get you through the trip. (I carry two spares just in case - crazy I know :new_Eyecr but... )

For the future . . . If you could go to 15 inch tires??? I have told myself that if my own personal 14 inch class D tire experiment blows up in my face or under my TM I would go to 15's next.

Very sorry to hear about the blowout. Very frustrating I am sure. Get on that computer and search around your next stop for a class D 14 and best of luck to you on the rest of your journey!

Thanks again for the post!

[brulaz]

"My TM tracks very slightly to the right due to the factory welding the axle about an inch or so (IIRC) further back on one side vs. the other. Could that contribute to failure, or would that just result in uneven wear, similar to a car out of alignment?"

??? An inch ??? Good grief, is this common? Our Elkmont tracks pretty well so hopefully they are a bit more precise these days.

I would think that any uneven wear indicates some stress on the tire.

[Wavery]

If it were me......I would install the lift kit and 15" wheels today......I would not risk ruining a nice trip like that over $500 or so. I'd just do it and be done with it........in fact, after reading this story, I will NOT make a long trip on my (now 1 year-old) 14" tires.

For our next long trip, I will do the upgrade ....100% guaranteed. I think that if you don't do it now, you will always be concerned about it. Not worth it, in my mind......

I'm really sorry this happened to you but it is a big help to me........ I have been kicking myself ever since I purchased my new 14" tires......

EDIT.....Is that a rubber valve stem on the tire that blew???

I am also suspicious of the fact that you are running a WDH. I hold to the theory that the shock-loading, on tires that are close to their maximum rating, may just be too much and lead to premature tread separation (which is what we are seeing in most of these incidents).

[mac_falls]

Looks like a rubber valve stem, bend to each side & check for cracks, if any, replace with metal valves & run with the same setup. Most problems have happened thanks to our asian junk valve stems! Replaced all 3 of mine before last summer & 2 were very badly cracked in both directions when bent to both sides.

[robertkennel]

Dave, Just curious, do you store your trailer outside or inside? If outside does the tire get a lot of sun? The roads can be poor, I wonder if they got pot holed. Robert

[Wavery]

Dave, Just curious, do you store your trailer outside or inside? If outside does the tire get a lot of sun? The roads can be poor, I wonder if they got pot holed. Robert
The Sun won't cause tread separation on a 3-year-old tire. Pot-holed....used a WDH....possibility.....;)

[ShrimpBurrito]

Thanks for all the responses. Just got back into an area where I can get internet with my computer so I could respond, however, I did read your responses right after they were posted. And for about a day and a half after reading those responses, my thought process was that the blowout was a fluke -- as Joseph eluded to, simply a combination of unfortunate series of events. The tire age, although not real old, not real young either, the fact that ambient air temp increased about 35 degrees in 2.5 hours, and the fact we went from sea level to ~1,500 feet in the same time period. Again, none of these factors should be an issue by themselves, but combined, perhaps they could cause a blowout. After all, the Kumhos had given me 3 solid years of infallable service.

But on the 3rd day, I got some good news and some bad news.

The good news: the plumbing shield I installed just a few days ago works. :D
The bad news: I had a second Kumho blowout about 48 hours and a few hundred miles after the first, this time on the opposite side, with the plumbing. The only remaining "unblown" Kumho was the spare, which by this time only had a few hundred miles.

This time, there are more tears in the sidewall, so I don't know if that helps isolate the reason for failure. I've attached pics of the second blowout. I'm hoping Bobby/wmtire will chime in here with his expert opinion. But being the second blowout in 48 hours, I quickly concluded that my "series of unfortunate circumstances" theory was wrong, and that clearly there was some other issue with the tires. Our elevation hadn't changed significantly, and the ambient air temperature had increased only 5 degrees since I last checked the cold tire pressure. Since all aspects of our towing configuration were no different that day than any other day in the past 3 years of trouble-free service, I concluded the failure was at least not related to elevation, ambient air temperature, or load.

Of course, it happened late Saturday afternoon, so many retail tire stores are already closed in Grand Junction, CO, and ALL tire distributors are closed. That means I am limited in what I buy to what whoever is still open happens to have in stock. It would have happened on a Sunday night on the 150-mile stretch of road in eastern Utah where there is ZERO civilization of any kind, so in that sense, I was lucky.

After some careful measuring and a test mount, I heeded the advice of many here on the forum (including Wayne in this thread) and upgraded to 15" wheels. Fortunately, I already had the lift kit, so that was not an issue. Not only did I not know of any other option, but given my choices on that day, it was my ONLY option. Since the only 14" tires I could find only had a load rating of ~1,800 lbs (which was the exact reason for going to the Kumhos to begin with), it was either get 3 of those, or go 15".

Unfortunately, the only 225 75/R15 they had in a trailer tire was a Carlise. I know, not ideal, although I seem to recall reading rumors that they are much improved over their previous disasterous reputation. But with a load rating of ~2,850 lbs (load range E), I am thinking I have a very large margin for error, and hope that will keep me out of trouble. And it wasn't really a choice....it was either the Carlise, or spend a few nights in Grand Junction till the distributors reopened on Monday, which was not an option.

The closest clearance on the 225's is at the wheel well covers -- it's only maybe 1/2", MAYBE 3/4". I put a half dozen flat washers between the TM and the cover on the bottom 2 screws to push the cover out a bit to give more clearance. I then chalked the sidewalls so I could easily tell if they were rubbing, and so far, so good. I wouldn't really expect the sidewall to flex very much on the top half of the tire, so I think it will be fine. And the tires run fairly cool. No more than luke warm on a 85-degree day.

The dealer only had black rims, and he added chrome lug nuts. I'm not a vehicle stylist by any means, but it looks snazzy. I can take pics if anyone is interested.

Dave

[B_and_D]

Hopefully these will get you through the rest of your trip and your trip "bad luck" will be over with and you can thoroughly enjoy the rest of it without further incident!

I am glad to hear that your plumbing cage worked, but on the other hand it doesn't look like too much came off of that tire before you pulled over & stopped? When we had our blowouts the whole tread section came off right away (in one big piece) and that's what caused the damage.

Good luck to you, and keep us posted on your adventures!

Dee

[ShrimpBurrito]

Dee - Yes, you are correct. The tread did separate, but didn't detach as it did in the first one. So it wasn't the ultimate test, I agree, but there were lots of pieces of rubber on the cage, and I saw a bunch fly off in the mirror as we pulled over.

Also, I forgot to add -- the dealer where I bought the 15"ers took my 14" Maxxis spare I had just bought and by this time had about 5 miles on it. In exchange, he gave me one of the 15" 225's at no charge.

To answer the other questions:

brulaz - Yes, the axle is not welded to the same point on the left and right sides. They are off by an inch. Check out this thread:
http://www.trailmanorowners.com/forum/showthread.php?t=6078. Given I will be at the factory next week, I may bring this up again in person.

wayne / Francis - The valve stems are not the old 100% rubber ones. There is a rubber seal around the rim, but then there is a metal stem coming out of the seal. They are rated for at least 100 psi, and maybe 125. A closeup view of the stem of here:
http://www.trailmanorowners.com/forum/showthread.php?p=41145&highlight=metal+valve+stem#post41145

Robert - Yes, my TM is stored outside, but in between 2 houses. Being that we live in SoCal, "in between 2 houses" means there is about 3-4 feet tops between each side of the TM and a house, one of which is 2 story. That means the tires see very little sun, so I don't think the failures were a result of UV damage.

Dave

[Wavery]

Dee - Yes, you are correct. The tread did separate, but didn't detach as it did in the first one. So it wasn't the ultimate test, I agree, but there were lots of pieces of rubber on the cage, and I saw a bunch fly off in the mirror as we pulled over.

Also, I forgot to add -- the dealer where I bought the 15"ers took my 14" Maxxis spare I had just bought and by this time had about 5 miles on it. In exchange, he gave me one of the 15" 225's at no charge.

To answer the other questions:

brulaz - Yes, the axle is not welded to the same point on the left and right sides. They are off by an inch. Check out this thread:
http://www.trailmanorowners.com/forum/showthread.php?t=6078. Given I will be at the factory next week, I may bring this up again in person.

wayne / Francis - The valve stems are not the old 100% rubber ones. There is a rubber seal around the rim, but then there is a metal stem coming out of the seal. They are rated for at least 100 psi, and maybe 125. A closeup view of the stem of here:
http://www.trailmanorowners.com/forum/showthread.php?p=41145&highlight=metal+valve+stem#post41145

Robert - Yes, my TM is stored outside, but in between 2 houses. Being that we live in SoCal, "in between 2 houses" means there is about 3-4 feet tops between each side of the TM and a house, one of which is 2 story. That means the tires see very little sun, so I don't think the failures were a result of UV damage.

Dave

I'm sorry that this happened. It must have been very stressful but I am glad that you upgraded and will most likely have a worry free rest of your trip.

My hunch is the 15" tires should last you a good 5 years with no concerns.

I'm going to upgrade soon......... I just have to recover from spending $500 on a PowerCaster PC2 trailer mover.......:p I like it but it suuuuuuuuuuuure iiiiiiiiiiis sllllloooooooooooooooowwwww. :cool:

[wmtire]

Dave, I have been reading up on your terrible tire troubles. Man, I hate this.

I am like you, and don't believe that temperature/elevation change is the culprit. Your tow vehicle tires went thru the same, without any trouble.

It is so hard to diagnose a tire that has a blowout, as far as the tread peeling off. It's hard to know if the tire blew, then the tread peeled from the run flat.......or if the tread peeled first, which caused the sidewall to blow. It can happen either way.

On tires that don't actually blow, but the tread peels off (and they still have air), then you can say for sure the tire separated (technically it's called tread delamination)

I am doing a lot of thinking on this. I'm already pretty sure of the answer, but do you check the air pressure in your TV tires when you check your tires on the trailer? Or does your Toyota have a Tire Pressure Monitoring System on it, so you don't have to check the pressure? There is a reason I am asking this.

[ShrimpBurrito]

My Toyota does have a factory TPMS, so while I don't check its tires as often, I do check them at least every time we take the TM on a trip. I think the last time I checked them was at home though right before we left, so I doubt that will shed any light on the situation, as you're probably looking for running temps.

While cool, they are pretty steady, however, so I rarely have to add or remove air.....maybe 3 times a year.

I do know that the Kumhos have been running pretty warm on this trip -- very warm during the first blowout, but the rim and hub were very warm then too. Unfortunately, however, while I routinely feel the hubs, I don't really remember ever feeling the Kumhos themselves prior to this trip, so I don't have a baseline reference.

On the second blowout, everything was cooler -- warmer than lukewarm, but not as how as before. That was expected though because the ambient air temp was 10-15 degrees lower (low 80's). The new 15" wheels and tires run slightly cooler (lukewarm) than the Kumhos in the same ambient temp.

Dave

[Joseph]

Oh man...

Very sorry to hear about the second blow out.

Glad to hear that the 15's fit and that the cage protected the plumbing!

Yes, do post a picture!..:)

Safe trip to you and hopefully all the bad is behind you now.


WMTIRE - Any ideas why it is that sometimes both tires pop on the same trip so close in time to each other? Seems that if both pop one behind the other, more or less, than what is causing them to pop should be common to both tires. If we as owners are doing all we can to insure a correct operating environment then the tire must be at fault? Or does the TM have something unique to it that makes it a little rougher on tires? Perhaps the axle being placed a bit farther back? Just wondering out loud sort of......:new_Eyecr

[ShrimpBurrito]

Reporting from Leavenworth, Kansas.....pictures are below!

[MudDog]

Your TM with the black rims is starting to look a little like that SpiderMan/Super Hero rig :D

Here's to hoping the rest of your trip is uneventful!!

[wmtire]

as you're probably looking for running temps.
Dave

Kinda sorta, but from a different angle........possibly in a low tire and how hot it gets.

I'm just trying to look at several things, but most likely it's going to be the tires themselves.........which I have stated from the beginning that only time would tell how well all of our alternatives held up.

The reason I originally asked about checking air pressure on the trailer (but not posssibly the TV), was the air pressure gauge itself. I have seen many of the air gauges (especially these .99 cent pencil gauges you see on a counter display), actually bend/break/damage the valve core. This is the spring actuated core in the middle of the valve stem that holds the air in the tire, that I'm talking about. When the gauge messes up the core, the tire will slowly leak air.......possibly down to the point where it would overheat and blow depending on the load.

Even the gauges we use here in the shop, do this from time to time....and we have to replace the core.

That's why I was trying to determine if you checked all your tires with this gauge or just the trailer tires. I would have guessed that if this gauge was damaging the cores, it would have damaged some on your TV too.........which you said you don't check near as much on, since they have a TPMS.

The two tires, both going out so close to each other, is what has me concerned.

I downloaded your pics and am going to let another tire dealer look at them tomorrow and see if he has an opinion, on why/if they delaminated.

I just hope you are thru with tires for awhile.

[Wavery]

Kinda sorta, but from a different angle........possibly in a low tire and how hot it gets.

I'm just trying to look at several things, but most likely it's going to be the tires themselves.........which I have stated from the beginning that only time would tell how well all of our alternatives held up.

The reason I originally asked about checking air pressure on the trailer (but not posssibly the TV), was the air pressure gauge itself. I have seen many of the air gauges (especially these .99 cent pencil gauges you see on a counter display), actually bend/break/damage the valve core. This is the spring actuated core in the middle of the valve stem that holds the air in the tire, that I'm talking about. When the gauge messes up the core, the tire will slowly leak air.......possibly down to the point where it would overheat and blow depending on the load.

Even the gauges we use here in the shop, do this from time to time....and we have to replace the core.

That's why I was trying to determine if you checked all your tires with this gauge or just the trailer tires. I would have guessed that if this gauge was damaging the cores, it would have damaged some on your TV too.........which you said you don't check near as much on, since they have a TPMS.

The two tires, both going out so close to each other, is what has me concerned.

I downloaded your pics and am going to let another tire dealer look at them tomorrow and see if he has an opinion, on why/if they delaminated.

I just hope you are thru with tires for awhile.

I'm thinking that it is merely a simple case of the tires breaking down due to stress. The 14" tires are fairly maxed out without a WDH. Placing and additional couple hundred pounds from just the tension of the spring bars and possibly several hundred pounds when hitting bumps, dips etc, has to shorten the life of the tires.

I went out this morning and bought 2' of 2" steel tubing. I'll be installing my lift kit this week and new tires & wheels in a few months.

Anyone interested in some 14" tires & wheels? The tires are ~one year old and have about 4,000 miles on them. I've never used a WDH with them.

[ShrimpBurrito]

Bobby - I too was actually just thinking about the tire gauge before I read your post, but not for the reason you explained as I am ignorant as to event you explained as even existing! But I was thinking perhaps that my gauge was inaccurate. It is not a .99 cent job, but it's not a super fancy thing either. It is made in the U.S., and I think it was maybe $10 or so, and looks exactly like this:

http://www.northerntool.com/images/product/images/15903_lg.jpg

But then I remembered that I measured the air pressure of the new tires before they were mounted, and the gauge read 80 psi. That is the max pressure of the tire, and that is the pressure the tech specifically said he inflated them to. So I know at least the gauge is accurate.

As far as damaging the valve core.....I use the same gauge to check my TV tires and have probably had it for 10 years. Through its use, I've never had a tire that was constantly losing air unless it had a foreign object in the tire. Even the TM tires held air pretty consistently.....I generally never had to air to them during the course of a trip....usually only once before our once-a-month trips, and even then, maybe just 2-3 psi. And often times they wouldn't need any air at all.

Speaking of gauges, I was thinking that a dial gauge would be more accurate and/or consistent. If that's true, have you seen any that you recommend strongly?

I just ordered the TST TMPS system for the trailer. It's being delivered to the east coast so I can install it for use for our return home. I don't know if it will help, but I don't know what else to do to improve my odds at this point.

Dave

[Joseph]

I like those rims....:) The TM has always reminded me of some sort of beach landing craft and those black rims fit the bill!....;) Here is hoping that the rest of your trip goes smooth with no problems. With a prayer on my lips and my fingers crossed for you!

Thank you for the pictures and sharing what is happening.

[grakin]

Just for grins...maybe use your gauge on your TV and compare it to your TPMS numbers, if that's possible...just to make sure the gauge is reading correctly. Or, better yet, two gauges on your trailer (with higher pressures than your TV).

[terryh]

I have been told that the best pressure gauge is the bourdon-tube type. I saw this on the CarTalk web site some years ago, bought one (direct from the manufacturer, not from CarTalk), and have been very pleased with it. It has a lifetime guarantee.

[gmferg]

The fact that the axle is attached out of alignment by 1" bugs me. I'm picturing the TM tires being constantly out of alignment and being dragged sideways. Could this have been contributing to all the blowouts since the beginning, and is it going to continue with the new 15s? I would like to hear WMTIRES opinion on this.

[M&M Hokie]

The fact that the axle is attached out of alignment by 1" bugs me. I'm picturing the TM tires being constantly out of alignment and being dragged sideways. Could this have been contributing to all the blowouts since the beginning, and is it going to continue with the new 15s? I would like to hear WMTIRES opinion on this.

I too am interested in this contributor because it has to add heat to the equation. I lack the experience to know just how much of this type of shear condition would be considered typical. I almost want to go crawl under my TM and see if I can do some measurements to check how square my install is. I never would have thought to check the axle/frame geometry.

[ShrimpBurrito]

Terryh - Thanks for the suggestion. I checked out the Cartalk page, and found the one you mentioned as manufactured by Accu-gage. The look just like the one I remember seeing as a kid, and since my Dad always bought quality, I know that must be it! I just ordered one of their bourbon tube gauges, and I'm really hoping it comes with some bourbon -- I think that may be all that can help at this point. Being that we're in the middle of a long trip, I'm going to attack this from as many angles as I can. This is the one I bought: http://www.getagauge.com/Tire-Gauges/Accu-Gage-RDF160X.cfm

The TST system I ordered was just announced (the 507RV). Unlike their earlier version, which several board members here have purchased, this version has user-replaceable batteries in the sensors, a suction cup mount, an easier programming procedure (no ID's required apparently), and supposedly a more friendly interface. They are expecting to ship the first lot within a week, so at this point, they only take orders by phone. It is announced here (http://www.tsttruck.com/Product_List.html).

I'll be at the TM factory Thursday morning. I hope they have their welders ready. :D

Dave

[Redhawk]

The local Discount Tire claims the Carlise's are the best they have and their #1 seller. Hopefully that will ease your concern a bit. You'd think if they were troublesome, we'd have heard about it by now. He was shocked when I ordered the Maxxis.

Sorry for your troubles...hope the rest of your trip is great!!!!

[Al-n-Sue]

John - you must go to the same Discount Tire I do - he pitched me the Carlisle's as well. I was tempted since they were rated E and were significantly less $$ - but I bought Maxxis as well. Only had one trip so far (to Cheyenne Mtn - so you know that was not a test! ) but we'll give them a longer shot this weekend - to Red Feather Lakes.

[Wavery]

The fact that the axle is attached out of alignment by 1" bugs me. I'm picturing the TM tires being constantly out of alignment and being dragged sideways. Could this have been contributing to all the blowouts since the beginning, and is it going to continue with the new 15s? I would like to hear WMTIRES opinion on this.

If the axle was not square with the frame, the trailer would not track straight. 1" out of square would be quite evident just by looking in your mirrors but to be sure, you could have someone follow you and see if the trailer favors one side.

My right side tire is about 1/4" from the rear frame member. The left side is 2" from the rear frame member. The difference is the location of the frame member, not the location of the axle mount.

The way to check is simply to measure from the front, outer edge of the tire to the center tip of the trailer hitch. The distance should be exactly the same.

[robertkennel]

Discount tire has some good trailer tire facts. Search "discount tire trailer facts". Robert

Or search "cedar rapids tire trailer facts" also good tips.

[Bill]

ShrimpBurrito posted... And the tires run fairly cool. No more than luke warm on a 85-degree day....

Dave -

Based on my experience with 15" Marathons (thanks, Bobby), you will find cool tires to be the normal situation. And you will enjoy the feeling of confidence you get each time you touch them. You've made a good move.

Careful, though. Don't panic, as I did, when one of the 15" tires felt quite a bit warmer than the other (not hot, but WARMER)! Turned out that the tire on the sunny side of the TM feels quite a bit warmer than the tire on the shady side. I've noted this several times since, and each time I have to calm my racing pulse.

Bill

[Wavery]

Dave,

Would you mind measuring the OD on your new 15" tires. I am installing a lift kit on my TM and I think that I will have to move my axle forward a bit (even after a 2.5" lift). I was thinking that I might move it 1" but I'm not sure that will be necessary to go that far. I currently have less than 1/4" clearance between my right tire and the frame member behind the tire. I'm actually surprised that the tire doesn't touch the frame at highway speeds.

Maybe wmtire already has that measurement. I thought that someone had posted them at one time but I can't find it.

[wmtire]

Maybe wmtire already has that measurement. I thought that someone had posted them at one time but I can't find it.

I don't have a measurement, but there is a formula that we use to get a real close approximation.

Say for example you have a metric sized tire of 225/75R15. The first number (225) is the section width. The second number (75) is the aspect ratio and the last number (15) is the rim diameter.

Here is the formula

(Section Width X Aspect ratio X 2) divided by 2540, then add rim diameter= approx tire diameter

(225 X 75 X 2) =33750

33750 divided by 2540 = 13.287

13.287 + 15 = 28.287 inches is approximate tire diameter.

You multiply the section width and aspect ratio by two, to give you the height of the two (or top and bottom) sidewalls of the tire.

You divide this result by 2540 because the tire size section width to begin with was in millimeters (225 millimeters). There are 25.40 mm to an inch, so we are converting it all over to inches at that stage and moving our decimal place (which we need to do to properly add it it to the wheel diameter which is given in inches). Technically, the aspect ratio is a percentage of the section width (or 75 % in our example). It's easier to just use a whole number and use 2540 in the conversion part. (instead of .75 and 25.40)

Now you take this converted number, which is the height in inches of the two sidewalls, and add it to the rim diameter (or hole in the middle of the tire).

You now have the approximate diameter of the tire in inches. It should work well enough to figure out your clearances, etc.

[Wavery]

I don't have a measurement, but there is a formula that we use to get a real close approximation.

Say for example you have a metric sized tire of 225/75R15. The first number (225) is the section width. The second number (75) is the aspect ratio and the last number (15) is the rim diameter.

Here is the formula

(Section Width X Aspect ratio X 2) divided by 2540, then add rim diameter= approx tire diameter

(225 X 75 X 2) =33750

33750 divided by 2540 = 13.287

13.287 + 15 = 28.287 inches is approximate tire diameter.

You multiply the section width and aspect ratio by two, to give you the height of the two (or top and bottom) sidewalls of the tire.

You divide this result by 2540 because the tire size section width to begin with was in millimeters (225 millimeters). There are 25.40 mm to an inch, so we are converting it all over to inches at that stage and moving our decimal place (which we need to do to properly add it it to the wheel diameter which is given in inches). Technically, the aspect ratio is a percentage of the section width (or 75 % in our example). It's easier to just use a whole number and use 2540 in the conversion part. (instead of .75 and 25.40)

Now you take this converted number, which is the height in inches of the two sidewalls, and add it to the rim diameter (or hole in the middle of the tire).

You now have the approximate diameter of the tire in inches. It should work well enough to figure out your clearances, etc.

Thank you very much Bobby....I knew that you would have the "Proper" answer.

[PopBeavers]

If I were to convert to 15 inch wheels, but install a low profile tire that so that the overall tire diameter is the same, what would I gain? I would think that the air volume would decrease, therefore making the tire run hotter.

I also have only 1/4 inch clearance as I back the TM into the garage.

Letting air out is not an option because I park it against a wall.

[saltbranch]

"My TM tracks very slightly to the right due to the factory welding the axle about an inch or so (IIRC) further back on one side vs. the other. Could that contribute to failure, or would that just result in uneven wear, similar to a car out of alignment?"

I would think this would have alot to do with your problem.I do question how you know its an inch off and how you measured it. The reason I ask is that I have built several single axle and tandem axle flatbed trailers. The way you measure is go to a point on the axle closest the to wheel and measure to the center of the ball hitch. I usually "eyeball" the ball hitch center and tape some string and let it drop with a fishing weight(plumb bob) tied on before it hits the ground. Then have someone hold the tape to the outer most common point on each side of the axle, measure to the string. I am good with a 1/4" difference. You cannot go from same side frame to axle measurements, think of the trailer as a triangle as thats what you are pulling, just a box mounted on top of the "triangle"
I have never used torsion axles, just leaf spring setups. I have never looked under my TM closely at the axle to be honest. Surely they are not welded in place, and are bolted in. The torsion axles mounts should be slotted to allow for adjustment. I cant say for sure, but a 1" difference would create wear and heat I would think.
Also when trailer is in storage are the tires covered? I know I have run into tire problems with a trailer at work that is not used much, but when loaded to near capacity I am having tires blowout that are 2-3 yrs old and these a 19.5 tire with less the 20k on them.