Tires for my fifth wheel

[andy29847]

I had a blowout on my 13,800# trailer. My tires were less than 2 years old and had ~5000 miles on them. I had checked the tires that morning and the pressure was at 80#s (load range E 16" tires rated at 3500#s). The trailer axle weight of my rig was just 10,280#s so I was well within specs. When I removed the other tires from the trailer, I found another tire that showed separated components and was close to exploding. Significant to me, all of the tires showed uneven tread wear - the outside edges were wearing faster than the middle. My conclusion, since I knew I had properly inflated the tires, was that the tires were not designed to carry the weight, or that the quality control of the construction process was inadequate. The tires were not good enough for the job they were being used for.







On the advice of a friend, I switched to Hankook LT7.5 x 16 Load Range G tires. These tires fit my rim and are a little taller than the original tires. The tires are actually rated at less load weight (3300#s) that the load range E tires I took off, but still well over the actual weight I carry. I have 6000 miles on the tires and they still look like new. The are speed rated at 65 mph and I adhere to that limit. Max pressure is 105#s and I make sure to stay over 100#s. I would say that the tire weight limit is set very conservatively (the air carries the load - the tire holds the air).

I also added a tire pressure monitor system for my piece of mind. The tire pressure monitor system shows that tire temperature and pressure are very stable when under way (100° outside temp, 108° tire temps, 120#s pressure, I-40, TX/OK border)

[dduerden]

In my past experience on trailers of all sizes the Goodyear Marathons are the best of the bunch in a common ST rated tire. I would never run any of the cheap off brand tires that generally come from the factory on a trailer. That said, they have their limits. if you are anywhere close to the weight rating, you will have problems, but at lighter loads they are the best of those cheaper tires. As my weight got closer and closer to the weight rating, the more tire problems I was having. Tread separations, sidewall distortions, broken belts, blowouts, you name it. If you check the Goodyear website they recommend overinflating the tires for higher speeds. I tried that, which was worse. I tried lowering the pressure by 10 psi, which actually seemed to help.

Short story long, I made the pricey switch to Hankook 17.5 load range H (4805# per tire) and they are absolutely bullet proof. I was going through 5-6 goodyears per season, and after 2 seasons with the 17.5's I have had zero issues, and have literally not even had to add air to any of the tires (I run a tpms system on the trailer tires). I spent $3k for 7 Hankook tires and Alcoa wheels, and am quickly paying that back in saved tires expenses. Not to mention peace of mind, I'm not constantly scanning the trailer tires in the mirrors for problems and just waiting on the next inevitable blowout. Money well spent. My second choice would have been the Goodyear G614 16", but they were actually far more expensive than the Hankook 17.5's (not counting the wheels).

LT tires are NOT constructed for trailer use, the sidewalls are not stiff enough and distort badly when turning. LT tires should never be used in trailer applications.

[Bamaman]

Goodyear Marathons are just another Chinese Will Pop tires of inferior quality. Maxxis M8008's are the only ST tire I'd consider putting on my fifth wheel trailer.

I looked at LT (E rated) tires to put on my fifth wheel. The R250 Bridgestones, Michelin Rib tires and G614 Goodyears are very popular replacements. I went with the R250's to replace the Chinese tires on my new fifth wheel trailer @ $195 each at Costco--very reasonably priced. They're very, very thick tires, and are 57 lbs. each--far heavier than any ST tire of comparable size. I talked to numerous tire store managers who had nothing but praise for the R250 and R500 Bridgestones.

Reading on numerous RV websites, I don't hear complaints on any of the above mentioned tires for RV use.

[andy29847]

dduerden writes;

LT tires are NOT constructed for trailer use, the sidewalls are not stiff enough and distort badly when turning. LT tires should never be used in trailer applications.

Tie Rack says:

http://www.tirerack.com/tires/tirete...jsp?techid=219

Trailer Tires vs. Passenger Vehicle Tires


There are differences in the driving requirements between the tires on your trailer and those on the car or light truck you used to tow it. Therefore there are distinct differences between the way trailer tires and tow vehicle tires are engineered.

Your tow vehicle is a leader, which means traction is a key focus in the design of its tires. Traction allows your tow vehicle to accelerate down the road, turn around the corner and brake to a stop. Another important consideration is tow vehicle tires are designed for ride comfort, which is achieved in part by allowing their sidewalls to flex.

Your trailer is a follower, which often makes tire sidewall flexing a negative. Sidewall flexing on trailers, especially those with a high center of gravity (enclosed/travel trailers) or that carry heavy loads, is a primary cause of trailer sway. Typical passenger radial tires with flexible sidewalls can accentuate trailer sway problems. The stiffer sidewalls and higher operating pressures common with Special Trailer (ST) designated tires help reduce trailer sway.

Also consider that Special Trailer (ST), as well as Light Truck (LT) tires are fully rated for trailer applications. This means ST- and LT-sized tires can carry the full weight rating branded on the sidewalls when used on a trailer.

However when P-metric or Euro-metric tires are used on a trailer, the load capacity branded on the sidewalls must be reduced by 9%. This means P-metric or Euro-metric tires with a maximum branded load rating of 1,874 lbs. for use on a car is only rated to carry 1,705 lbs. when used on a trailer.

Comparing the load capacities of a pair of tires of the same dimensions fitted to a single axle trailer, ST225/75R15 Load Range C-sized tires inflated to their maximum of 50 psi provide 4,300 lbs. of load capacity, where P225/75R15 Standard Load-sized tires inflated to their maximum of 35 psi would be limited to 3,410 lbs. of load capacity, a total reduction of 890 pounds.

Trailers will be more stable and pull better on tires designed specifically for trailer use. Since Special Trailer (ST) tires are constructed with heavier duty materials, they are tougher than typical passenger vehicle tires. This is a plus because trailer suspension systems are generally stiffer and less sophisticated than automotive suspension systems.

Special Trailer (ST) Tire Speed Ratings

Industry standards dictate tires with the ST designation are speed rated to 65 MPH (104 km/h) under normal inflation and load conditions.

However Goodyear Marathon and Power King Towmax STR tires featuring the ST size designation may be used at speeds between 66 and 75 mph (106 and 121 km/h) by increasing their cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.

Do not exceed the wheel’s maximum rated pressure. If the maximum pressure for the wheel prohibits the increase of air pressure, then maximum speed must be restricted to 65 mph (104 km/h).

The cold inflation pressure must not exceed 10 psi (69 kPa) beyond the inflation specified for the maximum load of the tire.

Increasing the inflation pressure by 10 psi (69 kPa) does not provide any additional load carrying capacity.

[andy29847]

An additional point....Generally, when RV owners switch from ST tires to LT tires, they select a tire with a higher load range. I went from ST tires rated E, to LT tires rated G. My feeling is that this completely eliminates any concern about using LT tires.


A question that no one has answered for me....

Given that the air carries the load, how can my ST Load Range E tires, inflated to 80 pounds, be rated for 3500 pounds while LT Load Range G tires, inflated to 105 pounds, are only rated for 3300 pounds?

I believe the answer is that the LT tires also have to be rated when considered the driving forces, and that the load ratings are much more conservative because of the variations of power used on the driving axle on the various vehicles that the tire might be used on.

I have absolutely no reservations about using LT tires on my trailer.

[SultanGris]

If your tires were 5 years old that's probably why, they can have perfect new looking tread and blow due to age. Also I know people who go 80 with trailer tires all the time with no issues, if it's rated for 65 I wouldn't worry about 70 at all, there is a margin there, they don't blow immediate when you hit 66mph, lol!

[WagonMaster]

Do a google for Sailun S637, 16" G rated tire. 110psi, so your wheels need to be able to handle the pressure. Extremely tough tire, an LT tire for trailers only, and really good reviews. I've replaced my Tow Max tires with these and now have a 75mph rated tire "G" tire I don't have to worry about.

[SkiSmuggs]

You didn't mention tire size that I recall, but the Maxxis M8008 E-rated tires are well regarded and are not made in China. I ordered a set from Amazon and had them mounted AND BALANCED locally. 7,000 miles and no issues and I keep them at 75-80 lbs of air. My fiver came with Load Range D "china bombs" which I replaced before taking a cross country trip. And ST tires are only rated for max speeds of 65 mph. Trailer tires should probably be replaced every 5 years regardless of mileage.

[jaycocamprs]

Put a set of R250's or XPS ribs on it and don't worry any more.

[Cjohnson52]

We had a blow out on our fifth wheel going to Montana. On our way back we had a flat tire on the same tire. None of the other tires have a problem. It is the left rear. Any suggestions. Trailer is 2 years old

[SkiSmuggs]

Originally Posted by Cjohnson52

We had a blow out on our fifth wheel going to Montana. On our way back we had a flat tire on the same tire. None of the other tires have a problem. It is the left rear. Any suggestions. Trailer is 2 years old

Probably a coincidence, but you should think about new quality tires all around.

[On the go]

This is a great conversation about tires. We have the Marathons on our new trailer with 7000 axels with GVWR of 16200 and are trying to decide the best tire replacement. Any advice appreciated.
joatay

[jenandjon]

I have a good one for you. The owners of my 5-er before me put passenger tires on it. It bounces horribly going down the road. I only pull it 12 miles each way to the campground a couple times a year but it still worries me. New tires this year I want go on some longer trips.

[FastEagle]

Originally Posted by On the go

This is a great conversation about tires. We have the Marathons on our new trailer with 7000 axels with GVWR of 16200 and are trying to decide the best tire replacement. Any advice appreciated.
joatay

DOT regulations do not allow RV trailer manufacturers to install tires with less load capacity than the vehicle’s axle ratings. Goodyear 16” Marathons even in LRE are only rated for 3420# at 80 psi. Check your trailer’s certification label. I’ll bet it lists your axles as having 6750# GAWR ea.

In any event, the Marathons are not stout enough for your trailer’s potential maximum load (GAW). Your options would be to use tires with more load capacity. ST options would be the ST235/85R16E rated at 3640# at 80 psi or the ST235/85R16F rated at 3960# at 95 psi. LT options offer steel/polyester cased LT235/85R16G tires from the USA or numerous off shore manufacturers that are rated at 3750# at 110 psi. Most of the polyester cased tires in that size will be hybrid ST tires that have higher speed ratings (75 MPH).

Whenever tires are plus sized, wheelwell clearances, axle spacing, rim dimensions and rim load capacities must be checked to insure all the fitments are safe.

FastEagle