Time for new tires? Fifth wheel

[partsman]

Okay, we bought a used 2004 fifth wheel in November last year, drove it home and here it sits, will be using it this summer, now I learned about date codes and find the tires on it are goodyear marthon ST225/75R15's and the date code puts them as being made in the sixth week of 2003, that makes them 8 years old, so they look great, see no checking or cracking, but I have heard that trailer tires should not be kept that long.
Any input on these, they are "C" rated, so will go "D" if I do have to buy new ones, as the fifth wheel if I read the label right is 9100lbs if I fully load it.

 

[Ramblin Fever]

Get new tires this year for sure.

We did the same thing you did...bought a used, barely used 30' 5th wheel, tires looked ok, but had a date code of 7yrs old and 2 developed bubbles in the sidewall just driving it home from the dealer.

Mine came with D-ply tires on it, I want to say that they're the same size you're listing for yours, but honestly I can't remember and it's dark/cold out right now.

But I do know it came with D-ply load rating tires as our 5th wheel is right at 7,200lbs empty; can be loaded to 10,500lbs with liquid in the tanks, cargo loaded in, etc....I have dual axles and a slideout.

I would definitely opt for D-ply tires, no harm can be done by doing this, you probably won't need as much tire psi however.

 

[partsman]

Thanks for the response, here is a pic of fifth wheel and some of the tires.

 

[CapriRacer]

Originally Posted By: Ramblin Fever
.....I would definitely opt for D-ply tires, no harm can be done by doing this, you probably won't need as much tire psi however.........


Sorry, but the load carrying capacity is dependent on the inflation pressure - it's just that a Load Range D can use more pressure, so you get more load carrying capacity.

So to get the true benefit of the higher capacity tires, you need to use higher pressure.

 

[The_Jeff]

Made in

Have read here of chinese trailer tires going pop, though it could happen to anyone.

 

[TireDude]

Hercules ST225/75/15 in a 10 ply rating.

 

[Ken2]

Originally Posted By: CapriRacer
Originally Posted By: Ramblin Fever
.....I would definitely opt for D-ply tires, no harm can be done by doing this, you probably won't need as much tire psi however.........


Sorry, but the load carrying capacity is dependent on the inflation pressure - it's just that a Load Range D can use more pressure, so you get more load carrying capacity.

So to get the true benefit of the higher capacity tires, you need to use higher pressure.

Yep. Remember, the air carries the load. The tire just holds the air.

Originally Posted By: HWEaton
Hercules ST225/75/15 in a 10 ply rating.
Hercules is just a tire distributor. The tires were probably made in the same Chinese factory that makes many other brands of trailer tires.

Partsman,
I agree with the others...new tires and go up to Load Range D. I'm an engineer who believes that everything that rotates should be balanced. People don't balance trailer wheels because no one is inside crabbing about the bounce, but suspension, bearings, tires, and stuff inside the trailer live longer with a smoother ride. Many trailer wheels are so cheaply made that the center pilot hole is punched out of the wheel somewhere near the true center. These cannot be correctly balanced the usual way on cones on the balancing machine. The tire shop must use their lug-centric adapter to balance these wheels correctly. Maybe yours are in fact in the true center, but make the shop prove it if they insist on mounting the wheel on the cone of the balancer.

 

[Ken2]

Originally Posted By: eljefino
Made in

Have read here of chinese trailer tires going pop, though it could happen to anyone.
Those are old GY Marathons. At that time they were made in Canada, before that in the U.S. Presently they're made in China, and I think all ST (Special Trailer) tires are Chinese...maybe a few from Taiwan. GY moved Marathon production to China, Cooper dropped out of the ST market, Michelin/BFG/Uni never was in that market (or has been out a long time), Conti/General is out of the market...anyone else in the U.S. make tires?

 

[CapriRacer]

Originally Posted By: Ken2
Yep. Remember, the air carries the load. The tire just holds the air......


Ken2,

As an engineer, do a free body diangram of the wheel. Notice that the air pressure pushing in on the rim is the same 360° around the rim. Ergo, there is no upward force vector caused by the contained air. Therefore the air is NOT holding up the vehicle, the tire is. The air is just pretensioning the tire, so it doesn't deflect as much under load.

 

[TireDude]

Originally Posted By: Ken2
Originally Posted By: CapriRacer
Originally Posted By: Ramblin Fever
.....I would definitely opt for D-ply tires, no harm can be done by doing this, you probably won't need as much tire psi however.........


Sorry, but the load carrying capacity is dependent on the inflation pressure - it's just that a Load Range D can use more pressure, so you get more load carrying capacity.

So to get the true benefit of the higher capacity tires, you need to use higher pressure.

Yep. Remember, the air carries the load. The tire just holds the air.

Originally Posted By: HWEaton
Hercules ST225/75/15 in a 10 ply rating.
Hercules is just a tire distributor. The tires were probably made in the same Chinese factory that makes many other brands of trailer tires.

Partsman,
I agree with the others...new tires and go up to Load Range D. I'm an engineer who believes that everything that rotates should be balanced. People don't balance trailer wheels because no one is inside crabbing about the bounce, but suspension, bearings, tires, and stuff inside the trailer live longer with a smoother ride. Many trailer wheels are so cheaply made that the center pilot hole is punched out of the wheel somewhere near the true center. These cannot be correctly balanced the usual way on cones on the balancing machine. The tire shop must use their lug-centric adapter to balance these wheels correctly. Maybe yours are in fact in the true center, but make the shop prove it if they insist on mounting the wheel on the cone of the balancer.


So if we are all agreeing here to go with the greatest load rating, why not go with the Load Range E Hercules? GY does not make a LRE ST, nor any others that I am aware of. If they are all offshore made stuff, why not go with the one that you can get with the greatest LRR?

 

[Nick R]

Don't know anything about these tires in paticular, but they definitely aren't chinese tires. Canuck quality

 

[Stewart Fan]

The only ST tires I would put on my fifth wheel are Maxxis or Denmans. The Maxxis are made in Taiwan,and the Denmans are from Mexico.

Both have recieved great reviews on RV.Net

I wouldn't put a chinese made tire on my trailer if you gave them to me.

Two years ago I went in a totally different direction though. I removed the chinese made 225/75/15s on my fifth wheel and replaced them with 225/75/16 Commercial T/A from BFG.

I did have to buy new 16" wheels,but they were only about $60 each for nice aluminum wheels from Sendel.

The BFG Commercial T/A has also been very popular on RV.Net

 

[Nick R]

Honestly the Chinese made kumhos on my focus aren't bad, minus the shocking treadwear and not great snow traction

 

[FordFocus]

I would recommend the Goodyear Marathon in a load range D over a 10 ply Hercules (Power Star) or the 10 ply Carlisle.

The GY is rated for 2540lbs x 4=10,160lbs @65psi
The Herc is rated for 2830lbs x 4=11,320lbs @80psi
The Carlisle is rated same as the Hercules for load capacity.

I have seen the Goodyear run the best at our shop over other brands. Also if your only 9100 lbs an 8 ply can handle the weight. And finnally if you run a 10 ply make sure your wheel can handle 80 psi. Not all trailer rims can. It says right on Carlisles site that the st225/75r15 LRE requires and HD wheel.

 

[WishIhadatruck]

I've heard that GY has moved many of the sizes of the Marathon's back to the USA for production after previously moving it all over to China. People at the trailerlife forum started reporting this about a year ago. Try to see the tires in person before buying to see where they are made. I bought my RV tires 2 years ago from Maxxis since they seemed to have the best reputation at the time, made in Taiwan.

 

[weebl]

I would personally replace these with LT tires. LT tires have been successfully used as replacements for ST tires by many trailer owners, with no negative effects, and in fact many positives, the biggest being a greatly reduced failure rate. LT tires are also OEM on a lot of trailers. There are naysayers who will insist you stick to ST. Here are the reasons I have for going with LT:

- lower failure rate
- no 65 mph speed limit, giving you a higher margin of safety
- greater selection of tires
- not forced to choose a "Made in China" tire
- not a neglected tire segment like ST seems to be
- used are replacements for ST tires by many
- factory equipped on many trailers
- typically, only radials available, some ST sizes are bias only

ST proponents will have the following points, possibly true, but I also have my counter points:

- ST tires have the required sidewall rigidity. True. LT tires also have good sidewall rigidity. Cousins in regards to sidewall construction to the ST line. They may have a little more give, but not enough to make a difference on trailers.
- ST tires have compounds resistant to UV fading for long term parking. If you're parking for that long, you should cover your tires regardless of the type anyway.
- ST tires are designed to sit idle for long periods, and will therefore last longer. By the time an LT tire shows signs of aging, you're likely at the 6 to 10 year mark anyway.

Look into Michelin XPS Rib if available in your size. It seems to be the LT tire to get for trailer applications. I'm sure there are other good choices as well.

 

[WishIhadatruck]

weebl is correct. If available in your size, get LT tires. The larger 5th wheel trailers often offer them as an upgrade or they are standard.

I think the only thing special about ST tires is that everyone is worried they will fail because it seems to be so common. With P tires and LT tires on our vehicles we worry about traction, cornering stability, etc. but you don't typically hear about failures unless they are underinflated or very old (2 things that may be more likely to be true about tires on a trailer).

 

[Stewart Fan]

Originally Posted By: weebl
Look into Michelin XPS Rib if available in your size. It seems to be the LT tire to get for trailer applications. I'm sure there are other good choices as well.


The reason I didn't go with the Michelins was the cost. The Commercial T/As I went with were over $100 per tire cheaper than the XPS.

You're correct about the XPS being the LT tire of choice though.

 

[FordFocus]

The Michelin XPS Rib and BF Commercial T/A's are not made in any 15" sizes so it isn't a option for many camper trailers that have 15". The XPS is a "All-Steel" tire which makes it more expensive than most tires in the same size.

 

[weebl]

The ST225/75R15 LRC on there right now have a capacity of 2,150 lbs. A choice I find good for the smaller sizes are the Continental Vanco2. You can get it in a slightly smaller 225/70R15C LRD (European equivalent to LT), which has a capacity of 2,470 lbs.