ST to LT tire upgrade question

[18CrewDually]

Originally Posted by MC9

I went with Transforce HT in 245-75-16 for my Cedar Creek 34RLSA. Very pleased.

X2. But I went with 235/85r16E on my Wildcat. The last set that the new ones replaced were also Transforce HT and they wore well over the years. 235/85r16 is a very common size and could be found practically any tire shop.

[cpaulsen]

Had 235/80/R16 on my Wildcat and went with LT245/75/R16 and never had any problems.

[Airdale]

Originally Posted by cpaulsen

Had 235/80/R16 on my Wildcat and went with LT245/75/R16 and never had any problems.

“Ultimately YOU are always responsible for the tires installed on your vehicle.”

Never assume you can simply substitute the tires shown in a load & inflation chart. Using the wrong size tire - whether too big or too small for your vehicle - can lead to sudden tire failure.

The reference provided is generally very similar to what all of the tire manufacturers are going to say about replacement tires. It’s a tire industry standard.

Help Me Choose The Right Tire | How to choose tires | Michelin US

Your tire installer let you down with your tire selection, in more ways than one. First is the size, it’s not even close to what the vehicle manufacturer had used for original equipment tires and certified on the trailer’s labeling and in its owner’s manual as being an appropriate fitment. A lot of people like to second guess OE tire fitments. That’s OK as long as they use replacements within the safety zone.

Your replacements require a minimum rim width of 6.5”. Your OE rims are most likely 6”. So maybe the installer said they would be OK? Safety is safety, either you do it or violate it.

There were better options for your replacements. They were probably more expensive but better and within existing safety standards.

[hbillsmith]

Originally Posted by Airdale

..."Of course the tire you are describing is probably the LT235/85R16G. Its sort of a hybrid tire built exclusively for trailer service. Its in the safety circle..."

Good info, thanks. As a followup, I've been doing a little research to compare whether I should replace my current Maxxis 8008's with same or go to the Sailun S637T. Both are ST235/80R16 and are labeled 'ST' tires specifically designed for Trailers. The Sailun's offers a few greater specs that are of interest to me. First, their single tire load range is higher (rated G vs. E), the carry capacity and speed rating are also greater. As for max speed, Sailun approves 75mph with 110psi. Of course, I need to confirm that my FR OEM HiSpec custom wheels are within spec for High Pressure and Rim Load.

For clarity, I created a side-by-side detail of all specs for both tires and it's in the PDF attached here. All the details came from mfg published specs.

[Airdale]

Originally Posted by hbillsmith

Sailun approves 75mph with 110psi. Of course, I need to confirm that my FR OEM HiSpec custom wheels are within spec for High Pressure and Rim Load.

Here is a reference for a type of rim needed for all LT235/85R16G tires rated at 3750# @ 110 PSI. Notice the rim size, 16X6.5” and the certification number. All rims are certified by the SAE.

TR8 | Sendel Wheels

I don’t have a reference for the newer ST235/85R16G tires with the higher 4080# load capacity.

[18CrewDually]

Originally Posted by Airdale

Here is a reference for a type of rim needed for all LT235/85R16G tires rated at 3750# @ 110 PSI. Notice the rim size, 16X6.5” and the certification number. All rims are certified by the SAE.

TR8 | Sendel Wheels

I don’t have a reference for the newer ST235/85R16G tires with the higher 4080# load capacity.

That's fine if you have 8 lug axles. 6 lug 16" wheels like the ones I put on my Wildcat do not have that high of a rating nor is it needed. Tire pressure is set at 80psi and the wheels are 6" wide with a capacity of 3200lbs. Ea.

[cpaulsen]

Originally Posted by Airdale

“Ultimately YOU are always responsible for the tires installed on your vehicle.”

Never assume you can simply substitute the tires shown in a load & inflation chart. Using the wrong size tire - whether too big or too small for your vehicle - can lead to sudden tire failure.

The reference provided is generally very similar to what all of the tire manufacturers are going to say about replacement tires. It’s a tire industry standard.

Help Me Choose The Right Tire | How to choose tires | Michelin US

Your tire installer let you down with your tire selection, in more ways than one. First is the size, it’s not even close to what the vehicle manufacturer had used for original equipment tires and certified on the trailer’s labeling and in its owner’s manual as being an appropriate fitment. A lot of people like to second guess OE tire fitments. That’s OK as long as they use replacements within the safety zone.

Your replacements require a minimum rim width of 6.5”. Your OE rims are most likely 6”. So maybe the installer said they would be OK? Safety is safety, either you do it or violate it.

There were better options for your replacements. They were probably more expensive but better and within existing safety standards.

Have worked with tires a long time.....did research and found the tires I used were more then enough for my 5th wheel. It towed better and felt better knowing I had a tire that worked. Mounted and balnaced them myself and after 5 years on them....still no problems.

[Tireman9]

Originally Posted by Airdale

Tire retailers would love to be able to say that but it's just not going to happen. All tires have a maximum load capacity molded right into their sidewalls.

The regulation for tire fitments to automotive and RV trailer axles are only intended to be used by those that they apply to, Vehicle Manufacturers, exclusively.

Automotive fitments must provide a percentage of load capacity reserves via recommended inflation pressures. That does not apply to RV trailer tire fitments which must provide the load capacity necessary to support total vehicle GAWR. GAWR on RV trailers is not always the same as the axle manufacturers actual load capacity. The Vehicle manufacturer has the authority to set GAWR as appropriate for each fitment.

I just wish the vehicle mfg demonstrated any willingness to take responsibility for their decision by offering and standing behind a full warranty. So far I have not heard of any doing so. You know what they say about those that take or hold authority but shirk any and all responsibility.

[bsmall]

Originally Posted by cpaulsen

Had 235/80/R16 on my Wildcat and went with LT245/75/R16 and never had any problems.

Yep, that's what I'm putting on mine this fall. Michelins Here I Come......

[hbillsmith]

Originally Posted by cpaulsen

Had 235/80/R16 on my Wildcat and went with LT245/75/R16 and never had any problems.

So did you use the same OEM Wildcat wheels that came on your Wildcat? If so, which wheels do you have (mine is a 2016 with Aluminum HiSpec wheels). Last question, are you running those LT's at 110psi or 80psi?

Thanks.

[Tireman9]

Originally Posted by hbillsmith

Assuming that the like-size tire swap LT for ST involved an LT tire that has:
- the same or more plys (tread and wall)
- the same or better load rating at both 80psi and 110psi
- the same or better real world user reviews

What's wrong with that?

Sorry missed your question.

Some false equivalencies.

Number of "ply" is meaningless and I could have 10 ply of polyester that are not as strong as one ply of steel.

There are no LT tires of the same "size" as ST type tire that are rated for the same or higher load capacity with the same inflation.

Since it is the air pressure not the tire that supports the load the only valid comparison of two different size or different type is when tires have same inflation.

Within a type (only ST or only LT) you will see that increases in air volume due to wider of larger OD or increase in inflation result in increased load capacity.

The above are just physics and facts not opinion.

[hbillsmith]

Originally Posted by Tireman9

"There are no LT tires of the same "size" as ST type tire that are rated for the same or higher load capacity with the same inflation."

Yep! I found that to be true also. I read a lot of good things about the Sailun S637 tire being a good LT to go for on upgrade but the size was a little off (LT265/75R16) compared to my OEM tires (Maxxis ST235/80R16) the LT's are G rated, the STs are E rated.

Turns out that Sailun markets an S637 tire in it's "ST" tire version matches the size but mfg specs are still 80psi and 65mph because that's the ST standard.

[hbillsmith]

NOTE: Some of the info I previously posted contains errors. Here are my revised/corrected notes:

My 2016 Wildcat 295rsx came with the Maxxis Tire upgrade. So what I have is Maxxis 8008 235/80R16 Load Range 'E', 3580# rated, 65mph speed, 80psi.

After about 13,000 trouble-free miles on the Maxxis's I was thinking about changing to the Sailun Load Range 'G' tires since Sailun now markets their S637 tire in an ST version that matches the Maxxis size. So if they are the same size I thought a Sailun tire upgrade would let me go 75mph safely (something I usually only do rarely).

Sailun's require a 110psi rated wheel and my Wildcat's original wheels are HiSpec Aluminum Series 9, 16", 6-lug rated for 3580# (matches what FR has on the trailers load sticker). BUT...no where does the sticker or any of HiSpec's website spec sheets specify the max PSI. So today I called HiSpec. They answered right away and the person I spoke with spent about 15 minutes with me researching the documentation at hand.

The result is that the wheels I have are the HiSpec Series 9 Aluminum wheel 16x6.5 size, bolt pattern is 6 lug and they are only rated 80psi. HiSpec also makes an 8-lug version that is rated 110psi.

So if I want to run Sailun's at 110psi and 75mph, I at least have to buy new wheels. Think I'll just stick with the Maxxis.

[sugarjohnson]

]The result is that the wheels I have are the HiSpec Series 9 Aluminum wheel 16x6.5 size, bolt pattern is 6 lug and they are only rated 80psi. HiSpec also makes an 8-lug version that is rated 110psi.[/B][/COLOR]

So if I want to run Sailun's at 110psi and 75mph, I at least have to buy new wheels. Think I'll just stick with the Maxxis.


My 2016 Wildcat 312BHX came with series 11 hi spec 16x6 and E rated Provider tires. I changed them out with series 09 HD 16x6.5 to match my Goodyear G614. Funny I also spoke with HiSpec as well as trailer tires and wheels who sells lots of these and BOTH confirmed these would handle 110psi with proper valve stems which were included when I bought the rims. Just got back from 4000 mile trip to Glacier and everything performed well. G614 ran about 116 PSI when hot and about 10 degrees over ambient temp whole trip. Conflicting info from HiSpecfor sure.

16" 6 Lug Series 09 Silver Hi Spec Aluminum Trailer Wheel

[hbillsmith]

Originally Posted by sugarjohnson

]..My 2016 Wildcat 312BHX came with series 11 hi spec 16x6 and E rated Provider tires. I changed them out with series 09 HD 16x6.5 to match my Goodyear G614. Funny I also spoke with HiSpec as well as trailer tires and wheels who sells lots of these and BOTH confirmed these would handle 110psi with proper valve stems which were included when I bought the rims...Conflicting info from HiSpecfor sure.

16" 6 Lug Series 09 Silver Hi Spec Aluminum Trailer Wheel

Took a look at the link and those are exactly my wheels. Nice to know your experience. I guess you are right, it depends on who at HiSpec answers the phone..;-)

[Tireman9]

Originally Posted by hbillsmith

Yep! I found that to be true also. I read a lot of good things about the Sailun S637 tire being a good LT to go for on upgrade but the size was a little off (LT265/75R16) compared to my OEM tires (Maxxis ST235/80R16) the LT's are G rated, the STs are E rated.

Turns out that Sailun markets an S637 tire in it's "ST" tire version matches the size but mfg specs are still 80psi and 65mph because that's the ST standard.

That Sailun shown with the sticker above has an "L" speed (75mph) rated version of the S637 in LR-G. I am reading good comments on the tire.

[Tireman9]

Originally Posted by hbillsmith

Took a look at the link and those are exactly my wheels. Nice to know your experience. I guess you are right, it depends on who at HiSpec answers the phone..;-)

If someone wants to claim a performance spec i.e. speed, load or psi rating then you should get it in writing. Web pages go out of date so get an email to see if they really have a product that meets the claimed spec. If they decline they I would certainly not trust what I am told verbally on the phone.