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Need Advice on Tires for Fifth Wheel

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Hi Everyone, Have been researching tires for my 35' fifth wheel before beginning fulltime 4/1, 11,590 gross trailer weight. I hope to get the tires installed on Weds. I was advised to upgrade from the existing ST225/75D15 to LRE 10 ply Load 125 radials. Have an appointment with Discount for Weds., and as of now it will be Carlysles (sp?). I have read good and bad on these. Discount said they can order others if I want. I know the time is fast approaching, but have been clearing house to sell. The tires will be in warm/hot climates. Any advice is very appreciated.

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After my experience with ST tires on my fifth wheel....3 out of 4 failing in the first year.....I would not recommend ST tires. Go at least a load range heavier than original and buy LT tires.

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Check out Bias ply trailer tires, they are cheaper and won't delaminate like the radials do which tear up the trailer skirting. I have been running G rated bias tires on my 14k fifth wheel trailer for 2 1/5 years now from Discount Tire for $160 each and have been very happy with them.

 

Greg

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Hi Everyone, Have been researching tires for my 35' fifth wheel before beginning fulltime 4/1, 11,590 gross trailer weight. I hope to get the tires installed on Weds. I was advised to upgrade from the existing ST225/75D15 to LRE 10 ply Load 125 radials. Have an appointment with Discount for Weds., and as of now it will be Carlysles (sp?). I have read good and bad on these. Discount said they can order others if I want. I know the time is fast approaching, but have been clearing house to sell. The tires will be in warm/hot climates. Any advice is very appreciated.

 

Your choice is the best and most reasonable one. Tires improve. Carlisle has vastly improved their radial trailer tires. Check the sidewall information. You may find that your size has also increased it's speed restriction and may even be made in the USA.

 

Have your rims checked by the installer to insure they will withstand the higher load capacity and psi needed for the LRE tires.

 

FastEagle

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I had read somewhere that LT (light truck) should not be used, that trailer tires have stiffer sidewalls than a truck, but don't have the time to look into it too much more. I hope the Carlysles are ok. If the E's don't fit on the existing rims, do I need to buy wheels too? Thanks for any help on this.

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I had read somewhere that LT (light truck) should not be used, that trailer tires have stiffer sidewalls than a truck, but don't have the time to look into it too much more. I hope the Carlysles are ok. If the E's don't fit on the existing rims, do I need to buy wheels too? Thanks for any help on this.

 

None of the 15” Light Truck (LT) tires provide enough load capacity to replace the tires you describe as being on your trailer. I assume they were the Original Equipment (OE) tires? However, there are numerous 16” LT tires that could be used. I’m sure that Forest River will not recommend LT tires to replace ST tires. The vast majority of the tire industry consider replacing ST tires with any other design a misapplication. The RMA - an independent organization - does not recommend replacing ST tires with any other design. So owners that do such a thing are on thin ice when/if misapplied tires fail. There are exceptions. Those hybrid LT tires designed by their manufacturers for trailer service.

 

Proper rim selection is a hand and glove process. They must be compatible with each other - so to speak.

 

 

FastEagle

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Well if it were me ...I would upgrade to the 16" LT tires but I swear I will NEVER buy another ST tire..they are junk. Just go into a tire store and lift an ST tire and then lift an LT tire...you will find that the LT tire is much beafier than the ST tire it will weigh much more.

 

I dont appreciate a tire less than a year old blowing out on me at hiway speeds.

Edited by Jimalberta

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I have had nothing but trouble with ST tires. Never again! ST tires are mostly junk. Just look at the speed rating and compare the tires. Buy a good LT tire rated to carry the ACTUAL load + a little buffer or fix flat tires. I will only use a commercial rated LT tire and I really like the Michelin XPS Rib, a 16 inch rim tire for loads up to the rated capacity. The last set of Carlisle tires I had came new on a boat trailer and didn't survive a year.

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X2 on the Michelin XPS Rib tires. I replaced my stock China bomb tires with these and have never had any problems. They have a beefy sidewall and are great on my 5th wheel. Many also recommend the Goodyear G-614 but you need a rim that can handle 110 psi. The Michelin are only 80 psi and will work on most any 16 inch rims.

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We have used the Carlisle tires in that size and load range and we had many issues with them including one blow out with only 5000 miles on them. Since 15" tire selections are limited and we could not afford to change out 6 rims to 16", we went back to Hercules tires as we had over 40000 miles on the set that were off another trailer. At that time they only had D rated tires and since then have come up with an E rated tire in that size that we went to last year. So far over 15000 miles on them. Make sure you run Tire pressure monitoring system and keep your speed to under 65 mph. Also when outside temps are hot really watch them and slow your speed down. With the E rated tires in that size, they need 80 psi and measure when they are cold and put them at max. pressure. Check your rims to be sure they can handle the 80 psi. Should be stamped on the rim.

Dave

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This might help you make your decision. It's a no brainer for me.

 

ST tires & LT tires are built to meet very different certification tests.

The gist of it is that ST tires must survive 4 relatively short testing cycles as follows:

 

FMVSS § 571.119 Standard No. 119; New pneumatic tires for vehicles other than passenger cars. wrote:

All testing at maximum load tire pressure.

 

2-hour test: 88% of tire maximum load rating at 50 MPH

30-minute test: 88% of tire maximum load rating at 75 MPH

30-minute test: 88% of tire maximum load rating at 80 MPH

30-minute test: 88% of tire maximum load rating at 85 MPH

 

OTOH, LT tires must meet far more severe certification tests:

 

NHTSA "LABORATORY TEST PROCEDURE FOR FMVSS No. 139" wrote:

 

Category B Endurance Test:

(LT "E" tire at 50 PSI)

4-hour test: 85% of tire maximum load rating at 75 MPH

6-hour test: 90% of tire maximum load rating at 75 MPH

24-hour test: 100% of tire maximum load rating at 75 MPH

 

Low Inflation Endurance Test:

(LT "E" tire at 37.7 PSI)

90-minute test: 100% of maximum load rating at 75 MPH

 

High Speed Performance Test

(LT "E" tire at 60 PSI at 75 MPH)

30 minute test: 85% of maximum load rating at 87 MPH,

30 minute test: 85% of maximum load rating at 93 MPH,

30 minute test: 85% of maximum load rating at 99 MPH

 

Note how the LT tire not only must endure far higher speeds during its certification test than the ST, they must survive these speeds while carrying its maximum rated load at less than normal tire pressure. In fact, the LT tire must survive carrying its max rated load at only 50% rated tire pressure at 75 MPH. It is only in the high speed test reaching speeds of 99 MPH that the LT is given the break of only having to carry 85% of its max load, although still at only 75% of its full air pressure.

 

As a result of the far more challenging conditions the LT tire is submitted to during its certification procedure, it is much more capable of enduring the heat developed at its rated load, especially at highway speeds.

 

This was lifted from the Arctic Fox owners site AFNash.com

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A lot to consider. I was going to have them installed tomorrow, but may procrastinate on it a bit, do some more research before hitting the highway. Taking my "new-to-me" fifth wheel home to its first park tomorrow, near my about to be listed s&b. Thanks everyone who has "weighed" in on this.

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just go to a good 16 inch wheel and LT tires and you will be happy but make sure the tire have at least 1 1/2 inches between the tires and the height is not to tall

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sts48

The D in the size designation of ST225/75D15 stands for Diagonal, which is descriptive of some aspects of the internal construction tire. Most RV tires used today are more often Radial tires. The tire size designation would look like this ST225/75R15. The Load Range Letter Designation could be after all of those numbers or it could be somewhere else on the sidewall as Load Range D or LRD (or E or even C). Load Range is a very generalized and non-specific comparative letter designation to identify different load carrying capacities of tires. It would be best to know the specific Maximum load carrying capacity that is stamped on the sidewall of the tire. This will say something like MAXIMUM LOAD SINGLE xxxx KG (xxxx lbs) AT xx kPa (xx PSI) COLD.

The standard specific maximum loads and associated Load Ranges for this size tire are ...

Load Range C - 2150 lbs. (at 50 psi)

Load Range D - 2540 lbs. (at 65 psi)

Load Range E - 2830 lbs. (at 80 psi)

 

So, first make sure to know exactly what you have now.

 

Knowing the load carrying capacity of the tires is the second most important thing when considering replacement tires. Knowing the actual loads that are on the tires is the most important thing. The only way to accurately get this information is to weigh the Truck and Trailer by wheel position. RVs often have hidden weight imbalance issues just because of their nature as homes on wheels. This is not bad it is just the way it is. Some are balanced and some are not. The problem is that when a RV is imbalanced this can cause corresponding tire overloading problems on one end of the axle in the location where the RV is heavier. This is a safety issue. The only way to know is to find out these things about your RV and the RV tires.

 

It is easy to get a new tire that will not be sufficient to carry the load. Even a really good tire will quickly fail if overloaded. It may last longer than a lesser tire but its life will be greatly shortened and can cause just as much havoc.

This often happens when switching from an ST tire to an LT tire. LT tires with similar Tire sizes as a particular ST tire do not have the same carrying capacity as an ST tire - the specific load carrying capacity is less. This does not mean that LT tires are poor choices for trailer use but care must be taken when switching to an LT tire. There are many LT tires. LT tires can be used for trailer application, but many are not well suited for trailer use because of their specific design (usually the tread). There are some very good LT tires that work very well for trailer use if the loads on a particular trailer allow for their application, but they are in the 16 inch tire size. There are not many LT tires in the 15 inch sizes. So, conversion to 16 inch tires and rims would likely be needed for LT tire use and there may be other issues with doing that. Axle hubs, axle/tire spacing, wheel well clearance are just a few things that might add more cost or limit the conversion to a larger diameter tire. So, switching to 16 tires is certainly an option but it could be costly. Research and more information would need to be determined

 

Maxxis makes a pretty good ST tire when the cost of conversion to a large diameter tire is not a viable option. These most likely would have to be ordered. They do make a ST225/75R15 in the Load Range E and if you currently have a lower load range then upsizing the carrying capacity is a very good thing.

 

It is important to emphasize that it is a very good thing to get weighed by wheel position before plunking down money on tires that will not carry the loads. Knowing this piece of information greatly helps to make sure one does not get a tire that is not capable of doing the job.

 

Finally, it is important to be diligent with air pressure maintenance and to know that almost all ST tires are speed rated to 65 mph. Exceed 65 mph (or any speed rating) for a sustained period of time will generate heat between the tread and the casing and leads to premature tire failure (most often tread separation).

Edited by TreyandSusan

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Be sure to note that a LT225/75R15 LRE is not rated to carry as much load as an ST225/75R15 LRE so you MUST confirm the load ratings of the tires you are considering.

Any "upgrade" should give you an INCREASE in load capacity of the tires.

 

Here is part 2 of a two part blog post with the steps needed when considering a change in tire type & size.

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This might help you make your decision. It's a no brainer for me.

 

ST tires & LT tires are built to meet very different certification tests.

The gist of it is that ST tires must survive 4 relatively short testing cycles as follows:

 

FMVSS § 571.119 Standard No. 119; New pneumatic tires for vehicles other than passenger cars. wrote:

All testing at maximum load tire pressure.

 

2-hour test: 88% of tire maximum load rating at 50 MPH

30-minute test: 88% of tire maximum load rating at 75 MPH

30-minute test: 88% of tire maximum load rating at 80 MPH

30-minute test: 88% of tire maximum load rating at 85 MPH

 

OTOH, LT tires must meet far more severe certification tests:

 

NHTSA "LABORATORY TEST PROCEDURE FOR FMVSS No. 139" wrote:

 

Category B Endurance Test:

(LT "E" tire at 50 PSI)

4-hour test: 85% of tire maximum load rating at 75 MPH

6-hour test: 90% of tire maximum load rating at 75 MPH

24-hour test: 100% of tire maximum load rating at 75 MPH

 

Low Inflation Endurance Test:

(LT "E" tire at 37.7 PSI)

90-minute test: 100% of maximum load rating at 75 MPH

 

High Speed Performance Test

(LT "E" tire at 60 PSI at 75 MPH)

30 minute test: 85% of maximum load rating at 87 MPH,

30 minute test: 85% of maximum load rating at 93 MPH,

30 minute test: 85% of maximum load rating at 99 MPH

 

Note how the LT tire not only must endure far higher speeds during its certification test than the ST, they must survive these speeds while carrying its maximum rated load at less than normal tire pressure. In fact, the LT tire must survive carrying its max rated load at only 50% rated tire pressure at 75 MPH. It is only in the high speed test reaching speeds of 99 MPH that the LT is given the break of only having to carry 85% of its max load, although still at only 75% of its full air pressure.

 

As a result of the far more challenging conditions the LT tire is submitted to during its certification procedure, it is much more capable of enduring the heat developed at its rated load, especially at highway speeds.

 

This was lifted from the Arctic Fox owners site AFNash.com

 

 

Some good research here. One important thing to remember is that all the above testing is done on brand new tires. NOT tires that are years old or that have thousands of miles on them or hundreds of pot holes or any miles when under-inflated or overloaded.

Just because a tire can run x mph for y hours does not mean it can run x mph for 2y hours or 10 months.at x-10 mph. You can not extrapolate individual performance.

 

All you can conclude form this comparison is that LT type tires have to run different testing then ST tires. INCLUDING lower load levels as LT tires are not rated to carry the same max load as ST tires.

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I had gotten several other opinions here that I hesitated to say what I got in order not to offend anyone. But since you ask, I got Hercules ST225/75 15" ordered through Discount Tire. I know many felt strongly with going with LT's or 16".

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Good choice, on the ST's, I tried running LT's on a 5vr, first tight camp ground I got into some of the tread came off due to the twisting of the tires, went back to ST's no problem. One other point to consider, I replace all trailer tires every 36 months regardless of tire condition, we have found that using tires beyond that time frame results in tire failures frequently. It's just not worth taking a chance on tire failures and body damage that comes along with it. Good luck.

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Good choice, on the ST's, I tried running LT's on a 5vr, first tight camp ground I got into some of the tread came off due to the twisting of the tires, went back to ST's no problem. One other point to consider, I replace all trailer tires every 36 months regardless of tire condition, we have found that using tires beyond that time frame results in tire failures frequently. It's just not worth taking a chance on tire failures and body damage that comes along with it. Good luck.

 

Sounds like the tread comming off was direct result of Interply shear. Changing tires at 3 years gets then off before the separation goes full width.

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Our 5er spends a 3 or 4 months a year in the garage but our last set of XPS Ribs lasted 10 years and still looked new. The previous set went about 9 years. The quality of the tire makes a big difference. I also try to avoid really tight turns especially backing but sometimes it is necessary. Lesser tires typically had at least one failure in 2 to 4 years on our trailers. We once had 4 Goodyear tires fail on 1 trip. When we bought the trailer it was 1 year old so these could have been damaged but the tire dealer told us Goodyear had a silent recall on the tires. These tires were 2 years old. Goodyear stepped up and paid for new tires and a few thousand in damage. The RV dealer in a small town said this was the 7th 5er like ours with Goodyear tires they fixed that year. We have owned numerous trailers from stock trailers to boat trailers. We finally tried to always buy a commercial rated tire to stop the constant tire failures.

Edited by Randy retired

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