sunvalleyjoe
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retro195man
My white walls are actually washing off lol
Besides,  safety is more important. 
I haven't taken the long journey yet. 
I'm definitely reading all these posts on here very closely before I do...
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Brandon Sailor

Peter we also are new owners of a 181b, (2017, used). We just towed over 1,000 miles home. Initially I was a little miffed because the tire doesn't have any specs on the sidewall that I could see. After a few hundred miles I found the sticker that gives the dimensions and was able to look behind the spare. Our trailer nets 32 and change, so we are really pushing the limit. Would be nice to have double axles. 

What pressure do you run in your tires?

I found that I felt safe at 60-65mph, occasionally at 70mph, a few times found myself hitting 75mph without noticing, but quickly slowed down. A couple 75mph didn't feel very safe, trying to get around a semi going down hill, I realize it's better to back off and try again on an uphill, lol. 

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sunvalleyjoe
If I had the option for my 150 . I would use 8 or 10 lt tires . St have a speed limit of 65mph . All the trailer we saw on last trip had LT tires . More options on which brand you can buy.
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mikes
There are ST tires rated for more than 65 mph. Even those which don't have a rating can be used at higher speed, provided they're not already at max load/pressure.

66-75 mph, add 10 psi (not going over max cold pressure)
76-85 mph, add the same 10 psi, and reduce max load by 10%

Source: Tire and Rim Association Yearbook (the "tire bible")

Correct me if I'm wrong, but the 150 came with Coker Classic 6.50-13 tires, which are rated at 1150@32psi (then derate to 1045 because they're passenger tires).

The closest metric would be ST175/80-13.  To match the 6.50-13 load capacity, a ST175/80-13 would run 1100@35 psi. Get load range C tires, and you can run them at 45 psi and be good to 75 mph. Run them at 50 psi and you're good for 75 mph and 1190 lb per tire.
Mike
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sunvalleyjoe
my st175/80r are 8 ply rated and big o says 50 psi 65 Mph are it. 150 came with 175 80 13 bias which cracked after 1 year. tire bible guys might not know all tire brand specs. Lt are the way to go. 
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mikes
The US Tire and Rim Association (TRA) is THE standards setting body for tires and rims in the US. Their members are the tire manufacturers and they set the specifications which the tire manufacturers follow. They're what makes a tire from one manufacturer interchangeable with one from another, installed on a rim made by a third. They're why every trailer tire of a particular size and load range is rated for for the same load at the same psi. It's why the sticker on the side of your trailer and car only has to show a tire type, size, and maybe load rating, and not a brand or manufacturer.

Big O, which is a retailer not a manufacturer,  only shows ST175/80R13 from Goodyear (Marathon) and Power King (Vanguard) in ST175/80R13 on their web site. But, for that size I can only find Load Range D (8 ply) from Kenda and one other name (which seems to be a distributor, not a manufacturer). Power King is part of TBC, the same parent company as Big O. Both are in turn part of Sumitomo. Goodyear, Sumitomo, and Kenda are all members of the TRA.

I'm sure that "the tire bible guys" know about the tires they make.

The reason to use an LT tire is that they have stiff sidewalls like ST tires, so don't need to be derated like P tires. They're available with higher loads for a given size (many P tires don't have a high enough load rating for trailer use). In some sizes, there's more choice than for ST tires. And, they may be of higher quality than ST tires, most of which are built to a price in China. But, you need to get to 16" rims before there are many choices.

BTW, a load range D ("8 ply") tire should have a max pressure of 65 psi. 50 psi would be for a LR-C ("6 ply") tire. You might want to check the sidewall. Big O apparently sold you a 6 ply as an 8 ply, or gave you the wrong max pressure.
Mike
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retro195man
Lol. You guys are making me nervous about my tires. I had to go out and check them today. I don't know if I should just get new ones now. 
H74-14 COKER CLASSIC 
these are only 4 ply tires. (Yikes)
1770 @ 32 psi

Does or did anyone have experience on the wear and safety of thes?
I might be going on a trip from Ohio to Arizona at the end of October. 
Let me know your experience. 

These are on a 195 double axel. 

20170921_155244.jpg  20170921_155300.jpg 
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sunvalleyjoe
I would replace them with ST tires made for trailers and radial looks like yours are bias ply and diff not trailer rated. just my opinion.
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mikes
1770/1.10 (Ptire derating, @ 32 psi) x 4 = 6430 lbs. capacity. Typical "dry" weight for a 195 is 3925.

Unless you're carrying bricks of lead, you should be fine.
Mike
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sunvalleyjoe

s vs. Passenger Vehicle Tires

(Lea en español)

There are differences in the driving requirements between the tires on your trailer and those on the car or light truck you use 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.

"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."

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 (

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retro195man
mikes wrote:
1770/1.10 (Ptire derating, @ 32 psi) x 4 = 6430 lbs. capacity. Typical "dry" weight for a 195 is 3925.

Unless you're carrying bricks of lead, you should be fine.

I get that. But I surly couldn't find the speed rating on these tires. And from what I could find they aren't listed as trailer tires.
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retro195man
sunvalleyjoe wrote:
I would replace them with ST tires made for trailers and radial looks like yours are bias ply and diff not trailer rated. just my opinion.


I am having the same thought. There just isn't enough info on those tires. I Lihue the idea of American stamped tires, at least you know everything about them. And I learned about ST tires.something I didn't know about before. 
Since I'll be driving approx 2000 miles one way mostly highway, it makes sense to ensure a speed rating of at least 65 mph.
I did run across a tire with 2 steel belts and 8 ply. Now I'll have to find them again! 

Thanks for your help in sorting this out and the well posted info about ST tires. 
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mikes
retro195man wrote:

I get that. But I surly couldn't find the speed rating on these tires. And from what I could find they aren't listed as trailer tires.
The speed rating is right there on the sidewall - "100P". 100 is nearest load rating to 1770 (1764). P = 93 mph.

They're passenger car tires, which is why the load rating gets derated (by dividing by 1.1) to get the rating for trailer use.

Don't worry about "these are only 4 ply tires. (Yikes)". That's what most tires, including trailer tires, are. A load range D trailer tire has an 8-ply rating, not 8 actual plies. It's historical, from way back when they used plies made of cotton for strength. Now they use stuff like steel and synthetic fibers to get the same strength from fewer plies and belts. My ST LR-E  "10-ply" tires have 4 plies - 2 steel belts and 2 polyester radial plies. Most semi-trailer tires have 5 plies, but may have a 16 ply rating.

Ply ratings were replaced with Load Ranges (B, C, D, E, etc.), but the actual capacity is different for different tire sizes, so they don't tell you anything directly. Now they use Load Indexes, like the 100 on your tires. Any tire with an index of 100 is load rated for at least 1764 lbs, regardless of size.

It makes no sense for someone with bias ply tires to search for ST tires in order to get more sidewall stiffness, and then choose radial ones. Bias ply tires have stiffer sidewalls than radials, so that's going one step forward and one step back.

I'm not sure where sunvalleyjoe's unattributed copy/paste came from, but it does have some factual errors.

I'd bet your Coker's are better quality than any ST tire you can find. Here's a video of how they're made.
Mike
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