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Old 03-24-2009, 05:41 PM   #15
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Originally Posted by Grand Master View Post
My '63 Tradewind weighs 3960 lbs. on the axle + 440 lbs on the hitch totaling 4400lbs.

My question concerning tire pressure is:
do I use the weight on the axle, or the total gross weight?

Mike Brumback
What are your tires rated to in weight?
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Old 03-25-2009, 10:10 PM   #16
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My tires are "D" rated Towmax radials. They have a 65 lb. max pressure rating.

As stated in an earlier post, my 1963 Tradewind weighs 3960 on the axle + 440 lbs on the hitch for a total gross weight of 4400 lbs. (loaded to travel).

According to Goodyear:
50 psi = 2150 lbs per tire (4300 lbs total)
55 psi = 2270 lbs per tire (4540 lbs total)
60 psi = 2380 lbs per tire (4760 lbs total)
65 psi = 2540 lbs per tire (5080 lbs total)

The question is............. what is the optimal tire pressure to balance safe load carrying ability, and "smooth" ride?

Thanks,
Mike
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Old 03-26-2009, 09:09 AM   #17
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Based on those numbers I would go with 55.
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Old 03-26-2009, 06:18 PM   #18
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Thanks for the reply. I aapreciate someone sharing their experience and knowledge.

I am amazed how difficult it is to get an expert opinion on something as simple as tire pressure. The tire manufacturer and retail agent had no opinion other than the max was 65 psi.

Airstream puts 65 psi in all of their trailers regardless of weight. I specifically called tech support and asked for the recommended tire pressure for a new 19' Flying Cloud (it is a single axle with a weight comparable to my '63 Tradewind). They stated 65 psi.

The Goodyear chart states that tire psi should reflect the trailer weight. It does not seem like a good idea to me to ever use the maximum rating.

I would appreciate other practical experience comments, but until I hear new information I am going to inflate my tires to 50 to 55 psi depending on how loaded the trailer is.

Mike
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Old 04-02-2009, 04:45 PM   #19
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I found that the new Airstreams have Goodyear Marathons on them. Rated to a little over 2500lbs a tire. This is what I will go with. Hope this helps someone wondering what kind of tires to get.
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Old 11-05-2009, 05:08 PM   #20
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Ok, so I found out Goodyears are not good, and are known for blowouts. I just bought 3 Towmaster 225 75 15 bias ply max psi 50 with a load rating of 2540 per tire. I'm just wondering if I should have gone with radials instead? I usually don't take long road trips, but will be driving to Ohio in the spring and was wondering if anyone knew if these tires would hold up alright? I have been reading alot about blowouts and it makes me scared for my body panels. Any advice would be great!
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Old 11-05-2009, 06:28 PM   #21
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Why 3? What is on the other wheel.

I am sure your trailer does not weight 10,160 lbs so why would you inflate to MAX pressure. Look at the inflation chart and inflate your tires to the correct pressure.

Tires properly inflated are not prone to have blowouts. Under inflation is the problem.
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Old 11-05-2009, 07:42 PM   #22
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2 for the axle 1 for the spare. the 2 tires together hold 5080lbs 2540+2540=5080. Now out of all the threads here and on boat forums this thread seems to help the most. I'm still wondering if the bias ply will work good for my situation any idea? Heres the thread from discount tire: The subject of tires is hard to escape these days. It seems every TV newscast or daily paper has a story on faulty automobile tires. As a result of negative publicity and a plethora of litigation, the tire industry is in the middle of self-analysis. Manufacturers, industry organizations and regulators are now coming forward with new recommendations concerning tire selection, maintenance and replacement.
Since knowledge and proper equipment are the keys to a pleasant, trouble-free towing experience, we decided to take a fresh and in-depth look at tires for trailers. The new information and thinking we uncovered from manufacturers surprised us.
For example, though your trailer's tires may sport plenty of tread and have healthy-looking sidewalls (that are free of cracks), the same tires may be disintegrating from within, manufacturers tell us. Like time bombs, tires can let go without warning.
A blowout on a single-axle trailer can spell disaster. A sudden shift in weight can create an unstable load and trigger a rollover. Yet, even on a tandem- or triple-axle trailer, the results can be unpleasant, and may spark a chain reaction as the remaining tires bear an overwhelming load and fail as a result.
Before we explore why seemingly sound trailer tires can fail, let's talk about selecting the right tires for your trailer in the first place. When it comes to trailer tires, what you don't know can hurt you.
THE RIGHT TIRES
When purchasing or replacing trailer tires, look for the ST (Special Trailer) designation. Avoid using a passenger car (P) tire or light truck (LT) tires, as these do not have stiff, beefy sidewalls and other structural components to provide stability and handle the stress and dynamics imposed by a trailered load. Modern ST tires feature materials and construction to meet the higher load requirements and unique demands of trailering.
"The major difference is reflected in the polyester cords used in ST tires," said Tim Fry, senior development engineer with Goodyear Tire & Rubber Co. in Akron, Ohio. "These cords are bigger than they would be for a comparable P or LT tire. Typically, the steel wire also has a larger diameter or a greater tensile strength to meet the additional load requirements.
"Because of the heavier construction for an equal volume of air space, an ST tire is designed to carry more load (than a P or LT)," says Fry.
What's more, the ratings on ST tires are standardized for axle ratings on trailers, according to Leo Garbarino, regional sales director for Carlisle Tire and Wheel Co. of Aiken, South Carolina. "If you have a 5000-pound axle, use an ST tire rated at 2540 pounds, so that two tires will meet the 5000 pound requirement in weight-carrying capacity," said Garbarino. "A P or LT tire is not rated the same way, so determining the load capacity can be difficult." If the combined tire ratings do not meet the axle ratings, the tires will eventually fail-perhaps in a catastrophic blowout.
Bias ply trailer tires normally have two belts of steel in the tread area and extra sidewall cords to add stiffness. Most tires also include nylon belts to help resist separation caused by overloading, underinflation or excessive speed.
FAILURE ANALYSIS
Even properly rated tires can fail. The No. 1 cause is underinflation. This is particularly true of an ST tire, which relies on proper inflation to live up to its load rating. Without enough air pressure, an ST sidewall will not function as designed, and will eventually fail, usually in the form of a sidewall blowout. Tires lose approximately 1 psi per month as well as 1 psi for every 10-degree drop in temperature. Overinflation is also hard on a tire, causing irregular wear and possibly a blowout. Yet, you can't always spot improper inflation with a visual inspection, so check your tires frequently with an accurate air-pressure gauge.
Long-term fatigue can also weaken a trailer tire. There are a number of factors that accelerate fatigue, but heat buildup from towing at high speeds is one of the main culprits, according to Fry.
"If you trailer nonstop from Phoenix, Arizona, to Las Vegas, in 100-degree temperatures at 65 mph, you use up much of the resources of that tire, and you don't realize it," said Fry.
Fry is not talking about wearing out the tread. It is the tire's construction that is breaking down. As heat builds up, the tire's structure starts to disintegrate and weaken. Over the course of several trips, this load-carrying capacity gradually decreases, according to Fry. Incidentally, all ST tires have a maximum speed rating of 65 mph.
One key to extending tire life on a tandem- or tri-axle trailer is to ensure that the trailer is riding level, thus distributing the load equally among all the tires. If the trailer tongue sits too high, the rear tires may bear the brunt of the load: with the trailer tongue too low, the front tires may be unduly stressed.
OLD MAN TIME
Time and the elements can also weaken a tire. The structural components and bonding agents slowly break down. This is due primarily to internal air pressure forcing oxidation of the tire materials. Ultraviolet rays also attack the rubber on a tire left exposed to the sun. As a result, a 15-year-old tire that was rarely used may look virtually new, but because of the ravages of time and elements, it does not have the same strength as when it was new, according to Fry. "As an estimate, in about three years roughly one-third of a tire's strength is gone, just because of the normal process of aging," Fry claimed. "We believe three to five years is the projected life of normal trailer tires."
REPAIRING ST TIRES
Should you repair a flat trailer tire? The answer depends on the size of the puncture, its location and method of repair. If it is a small hole in the tread area, it can be successfully patched. However, if it is a jagged cut or a puncture in the sidewall, replace the tire.
There is only one way to properly repair a flat tire, and it is important to have it fixed as quickly as possible. You must remove the tire and patch it from the inside. You must also plug the hole from the outside. If moisture gets into the tire and reaches the steel belt, the steel will begin to rust in seven to 14 days. Three months later, the rust will cause a weak spot in the tire. That will lead to a separation.
Whenever you repair or replace a tire, always put on a new valve stem. Heat and age deteriorate the rubber in the stem and this results in leakage.
RADIAL VS. BIAS PLY
One old wives' tale has it that you should never put radial tires on a trailer. The sidewalls on radials, the tale goes, are too soft, allowing the trailer to squirm all over the road. Conventional bias ply tires are the way to go. . . or are they? While radials were frowned upon at one time, today there is wide-spread acceptance of these tires. Which should you use? The decision hinges on your towing style, according to Ray Evans, executive vice president for engineering, marketing and sales of Titan Tire Corp. in Mogadore, Ohio. "While it is true that a bias-ply tire can provide more side-to-side stability than a radial, a bias ply also runs hotter than a radial," said Evans. "If you are pulling a heavy load, and need an extra measure of stability, use a bias ply." "On the other hand, if you do a lot of long-distance towing with a relatively light load at high speeds, the radial design may be better for you because it stays cooler than a bias ply," he said. The cooler the tire stays, the less it will fatigue.
IDENTIFY THE LOAD RANGE
The most critical factor in choosing a trailer tire is load range. You can find the load range molded into the sidewall of every tire. For towing, look for C, D and E load ranges. Load ranges are based on specific inflation pressures. With a higher inflation pressure, the tire can carry more weight. Therefore, a load-range C tire is at its peak load capacity when inflated to its maximum pressure of 50 psi. In range D, you need to be at 65 psi to handle the increased load capacity. Load-range E tires must be set at 80 psi.
Trailer Tire Load Limits (in lbs.) at Various Inflation Pressures PSI 35 50 65 80 ST115/80/13 880 (B) 1100 (C) ST165/80/13 990 (B) 1230 (C) ST175/80/13 1100 (B) 1360 (C) ST185/80/13 1200 (B) 1480 (C) ST195/80/14 1320 (B) 1610 (C) ST205/80/14 1430 (B) 1760 (C) 2040 (D) ST215/80/14 1520 (B) 1870 (C) ST205/75/15 1480 (B) 1820 (C) 2150 (D) ST225/75/15 1760 (B) 2150 (C) 2540 (D) 2840 (E) ST215/80/16 1820 (B) 2200 (C) 2600 (D) 2910 (E) ST235/80/16 2090 (B) 2600 (C) 3000 (D) 3420 (E) This table (above) shows the relationship between air pressure and load capacity for popular sizes of trailer tires. The capacities apply equally to radial and bias ply versions. The letters following some capacities indicate the load range.
In order to select the proper load range, you must first weigh your trailer fully loaded. This means full of water, LPG and gear. Go to a truck stop or public scale and weigh the entire rig. While you are there, weigh each axle separately. This will let you know if you have exceeded the tow rating of your tow vehicle or are overloading one of the trailer axles.
There are other considerations in picking ST tires. For the trailer tires to manage the weight, all must be identical. Do not mix bias and radials tires. What's more, the load range and size of each tire should be the same. And each should have the same amount of tread wear. This becomes critical when replacing a tire.
When replacing a single tire, always run the same size outside diameter tires on the same axle. A smaller- diameter tire will carry more weight, and may become overloaded.
After a blowout on a tandem-axle trailer, you should replace both tires on that side. The remaining tire was likely subjected to excessive loading and, as a consequence, may fail in the near future.
MAINTENANCE TIPS
When a trailer is in long-term storage, there are steps you can take to add life to the tires.
  • Put the trailer on blocks to take weight off the tires.
  • Lower the air pressure.
  • Keep the tires covered to protect them from the sun's ultraviolet light.
When taking the trailer out of storage, make sure there are no cracks in the grooves and no wire showing. Cracks in the sidewall could indicate interior damage or separations in the tire. MAXIMUM PSI?
As indicated earlier, maximum load range is attained only when the tire is at its maximum air pressure. Yet, should you maintain maximum pressure even if you are towing below the load range of the tires? Tire manufacturers differ on this point. "You should maintain the maximum pressure at all times," says Carlisle's Garbarino. "There is no advantage to taking air out of the tire. With maximum pressure, the tire will perform and wear better, and you will get better mileage. Reduce the psi, and you compromise the functionality of the tire."
Titan Tire's Evans feels differently. "If you want a little softer ride, drop the psi a bit," he says. However, he cautions that: "They have to know the actual load."
"Trailer owners should set the pressure according to the load," says Goodyear's Fry, who provided the tire pressure vs. load chart that accompanies this story. "Yet, this is not easy to do without weighing the trailer."
"Once the weight is accurately determined, the pressure should be set when the tire is cold, not when it is hot."
All the manufacturers agree on one point: If you do not know the exact weight of your trailer, keep the ST tires at the maximum cold psi.
Based on updated thinking, there are ultimately three keys to avoiding tire trouble while towing: (1) Make sure your rig is equipped with the proper tires: (2) maintain the tires meticulously: and (3) replace trailer tires every three to five years, whether they look like they're worn out or not.
As my grandfather used to say, take care of your equipment, and it will take care of you.
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Old 11-05-2009, 07:58 PM   #23
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From Above- ("If you trailer nonstop from Phoenix, Arizona, to Las Vegas, in 100-degree temperatures at 65 mph, you use up much of the resources of that tire, and you don't realize it.)

With that said and me having bias ply will I use up my tire resources driving 700 miles from Minnesota to Ohio? Should I return these bias plys and get radials Instead? Keep in mind I do about 58-60mph down the highway, and thats my top speed I'll go. I'm being a worry ward I know, but then again it's better to be safe then sorry. So anyone out there have any insight on my tires?
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Old 11-05-2009, 08:30 PM   #24
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Since I live in Phoenix and I tow in temperatures well in excess of 100 degrees all summer (it was 92 today), should I replace my tires every trip?

I run bias (LT) tires on my trailer. The set that was on the trailer when I bought it lasted over 8 years and started throwing some rubber. I should have replaced them sooner, that was my bad. The new set of bias tires have been on almost 2 years and I had one go bad on my last trip. It did not blow out, but developed a fairly large bubble where the sidewall and tread meet. I replaced it and did the last 1,000 miles with out any issues.
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Old 11-05-2009, 08:43 PM   #25
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Since I live in Phoenix and I tow in temperatures well in excess of 100 degrees all summer (it was 92 today), should I replace my tires every trip?

I run bias (LT) tires on my trailer. The set that was on the trailer when I bought it lasted over 8 years and started throwing some rubber. I should have replaced them sooner, that was my bad. The new set of bias tires have been on almost 2 years and I had one go bad on my last trip. It did not blow out, but developed a fairly large bubble where the sidewall and tread meet. I replaced it and did the last 1,000 miles with out any issues.
I appreciate your response. Are you running Towmasters as well?
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Old 11-05-2009, 08:54 PM   #26
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Yes, I have 7x15 LT bias Towmasters on my trailer. The previous tires were Carlisle 7x15 LT bias.

When I need a new Towmaster in Fort Collins, CO they could not find one near by. The replaced it with a Carlisle. When I got back home I replaced it with a Towmaster. Discount tire was very good about the replacements and my out of pocket cost was around $20.

It seems that different areas of the country carry different brands of tires. At least it seems that way with Discount Tire...
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Old 11-05-2009, 09:06 PM   #27
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Originally Posted by azflycaster View Post
Yes, I have 7x15 LT bias Towmasters on my trailer. The previous tires were Carlisle 7x15 LT bias.

When I need a new Towmaster in Fort Collins, CO they could not find one near by. The replaced it with a Carlisle. When I got back home I replaced it with a Towmaster. Discount tire was very good about the replacements and my out of pocket cost was around $20.

It seems that different areas of the country carry different brands of tires. At least it seems that way with Discount Tire...
So you would recommend towmaster bias ply?
Thanks again. You have made me feel better with my purchase.
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Old 11-10-2009, 07:29 PM   #28
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Ok, so I found out Goodyears are not good, and are known for blowouts. I just bought 3 Towmaster 225 75 15 bias ply max psi 50 with a load rating of 2540 per tire. I'm just wondering if I should have gone with radials instead? I usually don't take long road trips, but will be driving to Ohio in the spring and was wondering if anyone knew if these tires would hold up alright? I have been reading alot about blowouts and it makes me scared for my body panels. Any advice would be great!
I returned these today. I am worried about weight as well and the 10% margin you must be in on weight to be safe. I am looking at Towmaster radial st225/75/15 Load Range E max weight 2830.
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