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#1
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Trailer tires
Gang,
I'm leaving this Friday to pick up a glider that I purchased 1100 miles away. The trailer looks brand new, but is about 12 years old, as are its tires. The glider and trailer weigh in the vicinity of 950 #. The tire spec from the owner is : Carlisle Sure Trail ST ST205/75014 (replaces F78-14ST) Max Load 1760 lbs @ 50 PSI (actual load will be under 500 lbs) I plan to buy 2 new tires before the trip, and stop at the first service station after the pickup and have them mounted. Question is, what to buy. It does not appear that the trailer has any suspension, so I think I'd run the tires slightly soft, maybe 25-30 psi. I was wondering about whether it should be radial or bias ply? Any particular brands? Thanks in advance, Ed |
#2
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Trailer tires
Ed,
My research into this question resulted in me concluding that one should look at the Duro, Maxxis, Denman (in that order) tire brands. Goodyear Marathons are variable. Carlisle are not recommended (note that Carlisle also owns Titan). I chose Duros. Whatever you choose, make SURE that it is an ST tire - this stands for Special Trailer. And DO NOT run them at low pressure - run them at whatever the pressure is that is stamped on the sidewall to get maximum load carrying ability with minimum heat build up. As for the radial/bias question, radial tires are *not* recommended when lateral sway is a problem. However, radials do run cooler, and they provide a softer ride. I chose radials for my Cobra trailer, since sway has never been an issue, and there is no suspension. As for longevity, it's recommended that you replace trailer tires every 5 years. Although they may look "new", the sun and atmosphere damage the rubber. Finally, what kind of glider did you buy? -John On Jan 20, 10:14 am, flying_monkey wrote: Gang, I'm leaving this Friday to pick up a glider that I purchased 1100 miles away. The trailer looks brand new, but is about 12 years old, as are its tires. The glider and trailer weigh in the vicinity of 950 #. The tire spec from the owner is : Carlisle Sure Trail ST ST205/75014 (replaces F78-14ST) Max Load 1760 lbs @ 50 PSI (actual load will be under 500 lbs) I plan to buy 2 new tires before the trip, and stop at the first service station after the pickup and have them mounted. Question is, what to buy. It does not appear that the trailer has any suspension, so I think I'd run the tires slightly soft, maybe 25-30 psi. I was wondering about whether it should be radial or bias ply? Any particular brands? Thanks in advance, Ed |
#3
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Trailer tires
At 15:27 20 January 2009, jcarlyle wrote:
Ed, My research into this question resulted in me concluding that one should look at the Duro, Maxxis, Denman (in that order) tire brands. Goodyear Marathons are variable. Carlisle are not recommended (note that Carlisle also owns Titan). I chose Duros. Whatever you choose, make SURE that it is an ST tire - this stands for Special Trailer. And DO NOT run them at low pressure - run them at whatever the pressure is that is stamped on the sidewall to get maximum load carrying ability with minimum heat build up. I would Not do this. The pressure marked on the tyre is the maximum permitted inflation pressure. This would not allow the tyre to flex and only the central part of the tyre would be in contact with the road. It would also bounce all over the place on a rough surface. Inflate to the reccomended pressure for the trailer. If not available try 35-40psi If the trailer weighs considerably less than the max tyre load heat build up will not be a problem. Nigel |
#4
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Trailer tires
jcarlyle wrote:
Whatever you choose, make SURE that it is an ST tire - this stands for Special Trailer. And DO NOT run them at low pressure - run them at whatever the pressure is that is stamped on the sidewall to get maximum load carrying ability with minimum heat build up. Be aware ST tires have a 60 mph speed rating at the standard pressures. You can raise the rating to 70 mph if you inflate to required pressure for this higher speed. As for the radial/bias question, radial tires are *not* recommended when lateral sway is a problem. Cobra delivers all their trailers with radials. Go to the RV dealers and look at all travel trailers and 5th wheel trailers, and you will find out they are all riding on radials. That's because radial tires are far better tires, even for trailers. The bias ply tire's only advantage is it's a few dollars cheaper. If you compare a passenger car radial to a bias ply ST trailer tire, you might be right. However, radials do run cooler, and they provide a softer ride. And they are more road hazard resistant. I'm leaving this Friday to pick up a glider that I purchased 1100 miles away. The trailer looks brand new, but is about 12 years old, as are its tires. The glider and trailer weigh in the vicinity of 950 #. What is in it? It is worth weighing it if you are at all suspicious about the claimed weight. Assuming the 950 pounds is right... Unless you are towing this with a Volkswagen Beetle, it seems unlikely such a light trailer will cause any problems, regardless of the tires. The tire spec from the owner is : Carlisle Sure Trail ST ST205/75014 (replaces F78-14ST) Max Load 1760 lbs @ 50 PSI (actual load will be under 500 lbs) The ST inflation chart show a load rating of 850 pounds at 15 psi! This tire is serious overkill for the weight of your trailer. Even the smaller ST175/R13 has a 670 pound rating at 15 psi. If it were my trailer, I'd just put on passenger car tires with a speed rating about 20 mph higher than I planned to tow, and a 1000 or so pound load rating, then use the correct pressure for a 600-700 pound load. -- Eric Greenwell - Washington State, USA * Change "netto" to "net" to email me directly * Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4 * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more * "A Guide to Self-launching Sailplane Operation" at www.motorglider.org |
#5
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Trailer tires
Eric,
Thanks for the input. I've seen your helpful and enlightening posts on many subjects in this forum, so I'm certainly paying attention to your advice. My comments are inline below. On Jan 21, 12:34*am, Eric Greenwell wrote: I'm leaving this Friday to pick up a glider that I purchased 1100 miles away. *The trailer looks brand new, but is about 12 years old, as are its tires. *The glider and trailer weigh in the vicinity of 950 #. What is in it? It is worth weighing it if you are at all suspicious about the claimed weight. What's in it is a Russia AC4C, which weighs 330#. I've seen several pictures, and am not suspicious of the weight. The owner who I've talked to on the phone had no doubt of the weight, so I'm assuming he weighed it at some point. Assuming the 950 pounds is right... Unless you are towing this with a Volkswagen Beetle, it seems unlikely such a light trailer will cause any problems, regardless of the tires. *The tire spec from the owner is : Carlisle Sure Trail ST ST205/75014 (replaces F78-14ST) Max Load 1760 lbs @ 50 PSI *(actual load will be under 500 lbs) The ST inflation chart show a load rating of 850 pounds at 15 psi! This tire is serious overkill for the weight of your trailer. Even the smaller ST175/R13 has a 670 pound rating at 15 psi. If it were my trailer, I'd just put on passenger car tires with a speed rating about 20 mph higher than I planned to tow, and a 1000 or so pound load rating, then use the correct pressure for a 600-700 pound load. From my experience towing things, some of which is a glider, that's about where I was thinking of going. I have to buy the tires tonight, and unless I see some serious refutation of this idea here today, that's what I'll do. As far as the tire size, I'll probably try to get around the same rolling radius, as we've already bought a drop hitch to set the trailer level with the original tires. I'm sure I can have the dealer look up the recommended inflation pressure for that load. I've only seen some pictures of the trailer, and I was inferring that it had no suspension because there is probably only about 1-2" of fender clearance, and in the picture, I can't see that the fenders are free to move with the tires. Ed |
#6
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Trailer tires
At 12:26 21 January 2009, flying_monkey wrote:
I've only seen some pictures of the trailer, and I was inferring that it had no suspension because there is probably only about 1-2" of fender clearance, and in the picture, I can't see that the fenders are free to move with the tires. It seems unlikely, but still possible, that the trailer suspension has collapsed. More likely with one of those internal torsion setups - guys at the field have had trouble with fixing those. You might want to make sure what the situation is, because the fix could be expensive. Jim Beckman |
#7
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Trailer tires
Eric has a point - this is an unusually low weight glider/trailer
combination, and thus warrants a different approach. For the more typical glider trailer with 15m glider, though, I stick by my suggestion to use ST radials, as they have sidewalls specifically designed with trailers in mind. Their sidewalls are stiffer than a passenger (P) or light truck (LT) tire, are more flexible when cornering and backing, and are designed for extended, non-stop towing. Note that LT tires are also designed to carry higher loads than ST tires, so they're going in the wrong direction for a glider trailer. -John On Jan 21, 12:34 am, Eric Greenwell wrote: Assuming the 950 pounds is right... Unless you are towing this with a Volkswagen Beetle, it seems unlikely such a light trailer will cause any problems, regardless of the tires. The ST inflation chart show a load rating of 850 pounds at 15 psi! This tire is serious overkill for the weight of your trailer. Even the smaller ST175/R13 has a 670 pound rating at 15 psi. If it were my trailer, I'd just put on passenger car tires with a speed rating about 20 mph higher than I planned to tow, and a 1000 or so pound load rating, then use the correct pressure for a 600-700 pound load. |
#8
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Trailer tires
jcarlyle wrote:
Eric has a point - this is an unusually low weight glider/trailer combination, and thus warrants a different approach. For the more typical glider trailer with 15m glider, though, I stick by my suggestion to use ST radials, as they have sidewalls specifically designed with trailers in mind. Their sidewalls are stiffer than a passenger (P) or light truck (LT) tire, According to this page on the Subaru.com website about trailer tires, the ST is in between the passenger (P) or light truck (LT) tire in sidewall stiffness. http://tinyurl.com/9jesg They also mention ST tires better withstand storage and deterioration from the elements,including sunlight and ozone, due to the rubber formulations. -- Eric Greenwell - Washington State, USA * Change "netto" to "net" to email me directly * Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4 * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more * "A Guide to Self-launching Sailplane Operation" at www.motorglider.org |
#9
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Trailer tires
Well, folks, the die is cast. Last night I bought 2 Carlisle ST
205R75 tires. I'll let you know what happens. Ed |
#10
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Trailer tires
Eric Greenwell wrote:
jcarlyle wrote: Whatever you choose, make SURE that it is an ST tire - this stands for Special Trailer. And DO NOT run them at low pressure - run them at whatever the pressure is that is stamped on the sidewall to get maximum load carrying ability with minimum heat build up. Be aware ST tires have a 60 mph speed rating at the standard pressures. You can raise the rating to 70 mph if you inflate to required pressure for this higher speed. I didn't remember this correctly: According to a Goodyear general information sheet: Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph, it is necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the load. o Do not exceed the maximum pressure for the wheel. o If the maximum pressure for the wheel prohibits the increase of air pressure, then the maximum speed must be restricted to 65 mph. o The cold inflation pressure must not exceed 10 psi beyond the inflation specified for the maximum load of the tire. -- Eric Greenwell - Washington State, USA * Change "netto" to "net" to email me directly * Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4 * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more * "A Guide to Self-launching Sailplane Operation" at www.motorglider.org |
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