Last fall we took a trip to North Carolina, mostly on interstate to visit family. After returning from the 1500 mile trip, I noticed that the rear wheels had come into contact with the plastic fender trim and had also bottomed out in the wells. We travel with empty gray and black water tanks, ¼ full fresh tank. We almost always have less than 1100# of payload (3305 max capacity). Thinking I had a bad spring, I replaced all springs and shackles with a slightly higher capacity spring and wet bushings. While replacing a tire, I cut my hand of the tire I was trying to mount. I looked at the tire thinking there was a nail or piece of glass stuck in it, but found a small section of steel belt sticking out of the tread. I looked closer and found a bubble in the tread as well. These are the original tires (3 years old and about 6K miles), Power King Tow Max STR’s (ST225/75R15, D Range). I knew that the tires were probably not the best, but I thought I should get at least 10K miles out of them. The GVWR on my fiver is 9950 with tandem 4400 axles and rims 15” x 6” (J).Anyway, since I now have to replace the tires, I have been looking around the forums and internet. It seems like most people are opting for LT over ST tires. If I type in my tire size I get a lot of hits for the ST size, but very few for the LT size. Having read about a lot of D range tire failures I thought about upgrading to at least E range, but I have to check the rims for the maximum pressure/weight rating. I would hate to have to upgrade the rims as well, but I will if I have to. Anyone have any advice regarding the conversion from ST to LT? I cannot increase my tire size because the axles are already under the springs and I only have about 2” on average of well clearance.

No expert and often come here for advise but I don't believe you can use an LT tire of the same size because they don't have the same load capacity. You will probably have to go up in size. Give us the size of your current tires and others will be along to help.

For the size/weight FW you have, the same size D rated tire should be more than ample. I would just replace with a better quality ST tire. Many like the Maxxis brand. A couple others are Carlisle or Provider. I have the Provider tires on mine, and like them. They are speed rated to 81 mph.Jerry

If your wheels are 15" I recommend upgrading to load range E tires. Your wheels will need to be able to handle 80 psi. Maxxis make a good ST load range E. I had them on on my last trailer and felt much more confident than the power kings load range D's I was running.

After reading your post again I see that you only have 2" clearance in your wheel well. Have you bottomed out often? I can see where that would be a major problem.

You are right to replace them, the tread belt is separating from the carcass and expanding. On my last trailer I had an identical problem with all 4 Maxxis load range E tires that were 3-1/2 yrs old. So, even the best ST tires are not that great. I also thought the problem was with the suspension initially, but realized it wasn't since the tire was expanding side-ways as well.One more point, if you are towing nose high, then you have reduced clearance on the rear tires and contact over bumps and potholes could accelerate tire damage resulting in pre-mature failure.

Tire Problems and What to Upgrade To? | Good Sam Community

20 Replies

Dayle1
Explorer II
Mar 03, 2016
Scott M wrote:
Thanks, I checked my rims and that are rated to 2830#. Should there be a pressure rating as well? Looking at the E ratings, am I correct to assume that my rims will not handle the E Range tires at 3420#?

I am also maxed out on the height already. The unit came with under slung axles and clearance (unloaded) is already less than the 3" recommended by Mor-Ryde. I would have to have new shackle and center pivot brackets welded to the frame.

Actually, it is better to add a sub frame than to add longer shackles or longer mounts. The increased length means higher stress on the welds.
Scott_M
Explorer
Mar 03, 2016
I am towing within 1" of level, probably 1/2 to 3/4" nose high. Odd thing is that when we picked up the unit new from the factory, we adjusted the hitch to tow level and seemed to ride much higher off the ground with plenty of WW clearance.

When we came back from our trip to NC, the nose was riding a bit higher and I seemed to have lost clearance to the top of the well so I dropped the hitch an inch lower.

Also, one side had lost a significant amount of clearance (only about 1 3/8 of clearance from wheel to well) and I thought I had a bad spring. Replaced all four springs and the clearance improved a little bit. Also added bump stops and wet bushings. However the bad tire was on the side with the best clearance. Tanks are empty and the is very little payload on the trailer aside from set up stuff, a couple of bag chairs and some dishes. All totaled less than 500#.
Scott_M
Explorer
Mar 03, 2016
Thanks, I checked my rims and that are rated to 2830#. Should there be a pressure rating as well? Looking at the E ratings, am I correct to assume that my rims will not handle the E Range tires at 3420#?

I am also maxed out on the height already. The unit came with under slung axles and clearance (unloaded) is already less than the 3" recommended by Mor-Ryde. I would have to have new shackle and center pivot brackets welded to the frame.
alexleblanc
Explorer
Mar 03, 2016
not sure what your setup looks like but you may be able to raise your unit some and fit some 225/75R16 LT tires, they would be 1" overall diameter taller than your current ones are and they would offer a little over 200lbs more weight capacity so its not a downgrade.

If clearance is an issue now than you'll certainly not be able to run what I suggested without modifications to your unit's suspension.
laknox
Nomad
Mar 03, 2016
Scott M wrote:
Last fall we took a trip to North Carolina, mostly on interstate to visit family. After returning from the 1500 mile trip, I noticed that the rear wheels had come into contact with the plastic fender trim and had also bottomed out in the wells. We travel with empty gray and black water tanks, ¼ full fresh tank. We almost always have less than 1100# of payload (3305 max capacity).

Thinking I had a bad spring, I replaced all springs and shackles with a slightly higher capacity spring and wet bushings. While replacing a tire, I cut my hand of the tire I was trying to mount. I looked at the tire thinking there was a nail or piece of glass stuck in it, but found a small section of steel belt sticking out of the tread. I looked closer and found a bubble in the tread as well. These are the original tires (3 years old and about 6K miles), Power King Tow Max STR’s (ST225/75R15, D Range). I knew that the tires were probably not the best, but I thought I should get at least 10K miles out of them. The GVWR on my fiver is 9950 with tandem 4400 axles and rims 15” x 6” (J).

Anyway, since I now have to replace the tires, I have been looking around the forums and internet. It seems like most people are opting for LT over ST tires. If I type in my tire size I get a lot of hits for the ST size, but very few for the LT size. Having read about a lot of D range tire failures I thought about upgrading to at least E range, but I have to check the rims for the maximum pressure/weight rating. I would hate to have to upgrade the rims as well, but I will if I have to. Anyone have any advice regarding the conversion from ST to LT? I cannot increase my tire size because the axles are already under the springs and I only have about 2” on average of well clearance.

Sounds like the belts let go in the center allowing your tires to balloon out. Had that happen on both my last 2 sets when they died, though no rubbing.

There are no E-range LTs in 15", so you're stuck with STs in that size if you want to go to an E tire. Of these, the Carlisle RH and the Maxxis 8008 seem to be the best bet. Not that they might not have problems, as any tire can, but they seem to have much, MUCH fewer problems. Of these 2, Maxxis would likely get the nod as a better tire. I currently have the Carlisles, but would have gotten the Maxxis had time permitted. Going into the 3rd year with the Carlisles and they still look good. Covered and on boards while in storage.

Lyle
Dayle1
Explorer II
Mar 03, 2016
You are right to replace them, the tread belt is separating from the carcass and expanding. On my last trailer I had an identical problem with all 4 Maxxis load range E tires that were 3-1/2 yrs old. So, even the best ST tires are not that great. I also thought the problem was with the suspension initially, but realized it wasn't since the tire was expanding side-ways as well.

One more point, if you are towing nose high, then you have reduced clearance on the rear tires and contact over bumps and potholes could accelerate tire damage resulting in pre-mature failure.
Charlie_D_
Explorer
Mar 03, 2016
After reading your post again I see that you only have 2" clearance in your wheel well. Have you bottomed out often? I can see where that would be a major problem.
therink
Explorer
Mar 03, 2016
If your wheels are 15" I recommend upgrading to load range E tires. Your wheels will need to be able to handle 80 psi. Maxxis make a good ST load range E. I had them on on my last trailer and felt much more confident than the power kings load range D's I was running.
MFL
Nomad II
Mar 03, 2016
For the size/weight FW you have, the same size D rated tire should be more than ample. I would just replace with a better quality ST tire. Many like the Maxxis brand. A couple others are Carlisle or Provider. I have the Provider tires on mine, and like them. They are speed rated to 81 mph.

Jerry
Charlie_D_
Explorer
Mar 03, 2016
No expert and often come here for advise but I don't believe you can use an LT tire of the same size because they don't have the same load capacity. You will probably have to go up in size. Give us the size of your current tires and others will be along to help.

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Tire Problems and What to Upgrade To?

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