15" rim vs. 16" rim ?

[jcanavera]

Originally Posted by Tireman9

Ur right Jack. Switching to a larger, speed rated tire is a good way to get increased tire life. Do you by any chance have the comparison of safety margin of load capacity from when you were doing the calculations do learn what size & LR of LT type tire you needed?
I have seen a number of TT with OE ST type tires with margin of about 1% which is a long way from the suggested 15% minimum margin.

Well my current 225 X 75R 16" Michelin's have a 2680 lb load capacity at 80 psi. At max load that gives me 15%. I only do one 200 mile trip a year where the trailer is carrying that load. Typically I'm towing about 480 lbs lighter, which is due to my 60 gallon fresh water tank being empty.

Consider the 225 X 75 R 15" Maxxis E rated tires that these replaced had a 2830 lb. load capacity. At the time when I put on the Maxxis tires, I thought that the additional load capacity would address the issue of the stresses that my heavy Classic presented. The D rated Marathons that came with the trailer had a 2540 load limit at 65 PSI on 225 X 75R 15" D rating.

Nothing surprised me more was to return from a trip and discover that along that ride home (water tank empty) to find both Maxxis front axle tires had experienced belt slippage resulting in the tires ballooning. . Here's a picture of one tire shown next to a tire that hadn't failed.

What convinced me that ST tires were not in my best interest was this info from discounttiredirect. http://www.discounttire.com/dtcs/inf...erTireFacts.do. It pretty much lays out the case that ST tires lose 1/3 of their load capacity after 3 years. My belt failures occurring at the end of year 3 and the beginning of year 4 of use.

All of this really makes me believe that over time, ST tires aren't really up to the task of a trailer in my weight class. That's why I made the jump to LT's.

Jack

[nrgtrakr]

Aren't all of the tires on the trailer supposed to be the same? Same make, same size? ESPECIALLY for multiple axles?

[martian]

Originally Posted by jcanavera

Not quite sure if you want to do that. If you find that in your usage that the LT's give you good service, going back to ST tires might yield you a serous case of regret. I think many of us who made the jump to LT's haven't second guessed making the change. In the years I've been monitoring this topic, I've not seen anyone who made the 16" wheel, LT tire jump, come back here with regrets for doing so. As I noted earlier we are now approaching 4-5 years with member experience using LT's and we haven't seen them coming back with the issues we have seen with ST users.

Jack

Yep, I'm going to stay with the LT tires as I'm comfortable with them and have no reason to switch back to the ST tires. In my experience, the LT tire has outperformed the ST tire. (My trouble with the ST tire is described earlier in the forum string, if anyone cares to read it.) Again, thanks Jack for your input!

[jcanavera]

Originally Posted by nrgtrakr

Aren't all of the tires on the trailer supposed to be the same? Same make, same size? ESPECIALLY for multiple axles?

Same size and type, yes. Same make? I guess it depends upon how that set of tires holds up over the years. I've always used 4 of the same make, size, and age.

When my Marathon tire lost a section of tread, I replaced them all. When two of my Maxxis tires experience belt slippage at the same time, I replaced them all.

Failures like I experienced made me lose confidence that the others wouldn't experience the same problem shortly, so I replaced the entire set. If the tire was relatively new, I'd consider replacement of the single tire with a like kind. Once you get into later stages of tire life, 3+ years, you start having your doubts about the others if the failure is not caused by a road hazard.

Jack

[Tireman9]

Originally Posted by martian

I surrender Tireman9, this discussion has become too technical for my weak brain to comprehend. I would like your recommendation. When the time comes to replace my LT tires on the trailer, should I go to ST tires? What would be the best configuration (load rating & other specs) for a 27 to 31 ft Classic? Please don't respond with "It depends." I'd blow a fuse.

If you are running LT type tires and know that the rated load capacity of the current size LT tires equals or exceeds the load capacity of the original ST type tires then you should be good to go.

[Tireman9]

A question for all who have had failures on any type tire. Did you make the effort to file a complaint with NHTSA?
Not filing complaint does not give the regulators the data and numbers they need to justify considering initiating an investigation.

Recalls are the only way tire quality will really improve IMO.

You only need provide the TT or TV VIN and tire complete DOT serial (including date code). They don't need to know about your travel route or plans. Capturing a couple pictures if possible and let them know you have pictures available if they need. If there was damage include the total dollar amount.
Most of the time they will not contact you back but if enough people make the effort to file a complaint there migh actually be an investigation.

Remember you are working against the lobby efforts $$$$ of some in the industry who do not want tires or their application investigated or improved so numbers are needed.

[Tireman9]

Originally Posted by jcanavera

Well my current 225 X 75R 16" Michelin's have a 2680 lb load capacity at 80 psi. At max load that gives me 15%. I only do one 200 mile trip a year where the trailer is carrying that load. Typically I'm towing about 480 lbs lighter, which is due to my 60 gallon fresh water tank being empty.

Consider the 225 X 75 R 15" Maxxis E rated tires that these replaced had a 2830 lb. load capacity. At the time when I put on the Maxxis tires, I thought that the additional load capacity would address the issue of the stresses that my heavy Classic presented. The D rated Marathons that came with the trailer had a 2540 load limit at 65 PSI on 225 X 75R 15" D rating.

Nothing surprised me more was to return from a trip and discover that along that ride home (water tank empty) to find both Maxxis front axle tires had experienced belt slippage resulting in the tires ballooning. Attachment 250988. Here's a picture of one tire shown next to a tire that hadn't failed.

What convinced me that ST tires were not in my best interest was this info from discounttiredirect. http://www.discounttire.com/dtcs/inf...erTireFacts.do. It pretty much lays out the case that ST tires lose 1/3 of their load capacity after 3 years. My belt failures occurring at the end of year 3 and the beginning of year 4 of use.

All of this really makes me believe that over time, ST tires aren't really up to the task of a trailer in my weight class. That's why I made the jump to LT's.

Jack

Your situation should have resulted in an adjustment from tire dealer IMO.
Also classic good example of tires that justify a NHTSA complaint being filed.

[Tireman9]

Did a two post series on my blog. June 23, 2014 and July 15, 2014 on topic of ST to LT switch. Was aimed at 5th wheel TT but all the info applies to anyone considering making the change.
You have to check my profile for info on my blog.

[Tireman9]

Originally Posted by SSquared

This seems like a major point: I think you are saying, an ST tire rated for a load capacity of X has less real-world load capacity than an LT tire rated for X.

Tireman, is there any rule of thumb or SWAG that would say what percentage difference it would be? Or is it two much apples and oranges? And would the same be true for comparing an ST tire rating to a P tire rating?

Did a blog post with numbers back in September 14, 2011 that shows the spec load capacity difference between different "type" tires that many might consider to be the same "size".

in the example the load capacity ranged from 1,377# to 2,340# depending just on application. All had essentially same OD and width and were on 15" rim.

[Tireman9]

Originally Posted by nrgtrakr

Aren't all of the tires on the trailer supposed to be the same? Same make, same size? ESPECIALLY for multiple axles?

Never seen anything indicating that trailer tires must be "same make, brand and size)

But I would suggest that for consistent response, especially in an emergency situation all tires on a TT should have be same size and inflation.

TT are probably a bit less critical than TV.

Fronts of TV should be same make, model, size and same inflation.

Rears in dual application should definitely be matched in pairs to be same brand, design, inflation and even measure similar OC within +/- 3/4"

I have covered matching duals in my blog.

[jcanavera]

Originally Posted by Tireman9

Your situation should have resulted in an adjustment from tire dealer IMO.
Also classic good example of tires that justify a NHTSA complaint being filed.

Problem for me is that there is no local outlet for Maxxis tires in the metro St. Louis area. I got these from a dealer about 140 miles southwest of us. My neighbor was working at the time in that area so it was easy for him to pick them up for me. I wasn't up for a 280 mile trip and then that lingering concern that the other two tires on the rear axle may be on their way to a similar fate. Once you lose confidence in a product, using it again is difficult. Especially with the fact that I was extremely lucky in catching these prior to a failure on the road.

Jack

[Phoenix]

Tireman9, you keep repeating that "interply shear" is the primary cause of ST tire failures. Before switching to 16" wheels and LT tires, I had 3 of 5 ST tires fail with tread separation (two GYMs and one Maxxis).

Our 19' Bambi has a single axle, so interply shear is not a significant factor when towing, backing, etc.

We now have about 40,000 miles on our 275/75x16 Michelin XPS Ribs (LT, load range E, inflated to 80 psi), and have had absolutely no tire problems in 4 years.

How do you explain the difference between ST and LT tire reliability on our Airstream?

[Tireman9]

Originally Posted by jcanavera

Problem for me is that there is no local outlet for Maxxis tires in the metro St. Louis area. I got these from a dealer about 140 miles southwest of us. My neighbor was working at the time in that area so it was easy for him to pick them up for me. I wasn't up for a 280 mile trip and then that lingering concern that the other two tires on the rear axle may be on their way to a similar fate. Once you lose confidence in a product, using it again is difficult. Especially with the fact that I was extremely lucky in catching these prior to a failure on the road.

Jack

Well even if trying to get the dealer to take responsibility. You should still have filed a complaint with NHTSA.

All the complaints in the world posted on an RV forum will never result in a recall or forced improvement in tire quality or improved fitment requirements.

[jcanavera]

Originally Posted by Tireman9

Well even if trying to get the dealer to take responsibility. You should still have filed a complaint with NHTSA.

All the complaints in the world posted on an RV forum will never result in a recall or forced improvement in tire quality or improved fitment requirements.

Point well taken. In retrospect I probably should have but I really wasn't aware of that avenue at the time of the failure. Bottom line, folks selling me bad products no longer get my business any more. In some cases I think there is more power in making others aware of the issues and making them think twice about about their options when having to replace their ST tires.

Just looking at the number of tire threads and those going to LT's are making ripples. Airstream is a prime example of a company who obviously is hearing the call. You now have options, you now have models that come with LT's. There are 5th wheels being made that come with LT's. Things are changing and sometimes the power of social media can exert change.

As you are aware this is just not an Airstream issue. If you look at other RV forums you will find threads related to the ST tire issue.

Jack

[Tireman9]

Originally Posted by jcanavera

Well my current LT225 X 75R 16" Michelin's have a 2680 lb load capacity at 80 psi. At max load that gives me 15%.
snip
Consider the ST225 X 75 R 15" Maxxis E rated tires that these replaced had a 2830 lb. load capacity. At the time when I put on the Maxxis tires, I thought that the additional load capacity would address the issue of the stresses that my heavy Classic presented. The D rated Marathons that came with the trailer had a 2540 load limit at 65 PSI on 225 X 75R 15" D rating.
snip
All of this really makes me believe that over time, ST tires aren't really up to the task of a trailer in my weight class. That's why I made the jump to LT's.

Jack

Jack, your numbers provide a great example of part of the reason people have problems with ST type tires and better luck with LT.

Given that a tire's load capacity is a function of its air volume and pressure with durability affected by speed of operation I think you may be able to understand that the smaller ST tire with its over-stated load capacity is more prone to failure.
Maybe if speed limits were still 55 mph ST tires would be able to deliver acceptable durability but almost no one is willing to tow at 50 with only occasional runs up to 55.

People seem to forget that the load capacity for ST tires still use the same formula developed in the '60's while today's Passenger and LT tires follow 21st century formula and regulatory testing which is much more stringent.

I doubt that people change their driving habits if/when they change tire type so we shouldn't be surprised when we see a tire with a more realistic load capacity claim and higher speed capability delivers better durability.

IMO the formula and regulations will never improve unless the industry is forced to do so by the regulators and the regulators will never be able to go against the RV industry and low cost tire makers unless they have lots of data (complaints) to back them up but the RV owners as a group just seem to prefer complaining around the campfire, or on an RV forum rather than taking the 10 minutes it takes to file a complaint with NHTSA.

[Ron A]

Originally Posted by Tireman9

Jack, your numbers provide a great example of part of the reason people have problems with ST type tires and better luck with LT.

Given that a tire's load capacity is a function of its air volume and pressure with durability affected by speed of operation I think you may be able to understand that the smaller ST tire with its over-stated load capacity is more prone to failure.
Maybe if speed limits were still 55 mph ST tires would be able to deliver acceptable durability but almost no one is willing to tow at 50 with only occasional runs up to 55.

People seem to forget that the load capacity for ST tires still use the same formula developed in the '60's while today's Passenger and LT tires follow 21st century formula and regulatory testing which is much more stringent.

I doubt that people change their driving habits if/when they change tire type so we shouldn't be surprised when we see a tire with a more realistic load capacity claim and higher speed capability delivers better durability.

IMO the formula and regulations will never improve unless the industry is forced to do so by the regulators and the regulators will never be able to go against the RV industry and low cost tire makers unless they have lots of data (complaints) to back them up but the RV owners as a group just seem to prefer complaining around the campfire, or on an RV forum rather than taking the 10 minutes it takes to file a complaint with NHTSA.

Thank you well said. Without reading your post I am like many, I did not know about how to register my complaint. Thanks again for your input and your blog.


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[jcanavera]

Here's the link to the site. https://www-odi.nhtsa.dot.gov/ivoq/Complaint.cfm

But understand the industry is stacked against us. From my own experience with a road hazard warranty on a claim, the dealer will use every trick in the book to throw the blame on you. I picked up a nail on my car tire and the tire deflated quickly. I got off the road quickly and got the spare on. Dealer confirmed that I had a puncture that was just outside of the tread. Not repairable due to the location. Hazard warranty claim denied due to debris inside the tire indicating the tire was rolling while flat. I noted that I was rolling when the tire suddenly deflated and yes it was rolled on as I was getting to the shoulder of the road. I protested to the manager and he made an "exception" and allowed the adjustment for road hazard damage. So much for tire forensics and my confidence in the industry to root out tire defects.

Most of us lack the proof or the facilities to prove the weight of our vehicles, tire pressures, and speed that our tires were at when the failure occurred. Without the forensics which are hard to provide, simply asking for an allowance from the dealer is like pulling teeth.

Jack

[m.hony]

After I bought 16" wheels, tires, Dill TPMS, and Centramatic balancers, I realized a Firestone TransForce HT LT 235/75R15 Load Range E 10-ply tire was available and in stock at the local Southern Tire Mart. I wonder if that same tire is available in a 225/75R15 or if the 235/75R15's would fit. I could have save about $800 to buy tires only or saved $400 to not buy 16" wheels and kept my 15" wheels which I sold for $200. Also, the 15" tires were about $40 less each- $160-
Did I screw up?
Maybe-


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[martian]

Originally Posted by Tireman9

If you are running LT type tires and know that the rated load capacity of the current size LT tires equals or exceeds the load capacity of the original ST type tires then you should be good to go.

Thanks for the response Tireman9! Yes, my current LT tires have a higher load capacity. Best Wishes!

[daveswenson]

Originally Posted by m.hony

After I bought 16" wheels, tires, Dill TPMS, and Centramatic balancers, I realized a Firestone TransForce HT LT 235/75R15 Load Range E 10-ply tire was available and in stock at the local Southern Tire Mart. I wonder if that same tire is available in a 225/75R15 or if the 235/75R15's would fit. I could have save about $800 to buy tires only or saved $400 to not buy 16" wheels and kept my 15" wheels which I sold for $200. Also, the 15" tires were about $40 less each- $160-
Did I screw up?
Maybe-


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The only Transforce HT tires I can find in the 235/75R15 are Load Range C. Are you sure they were E?