I picked up a new to me trailer and it needs tires, however I'm not fluent in old tire sizes. Obviously they are 15", but I'm used to looking at radial tire sizing.
I picked up a new to me trailer and it needs tires, however I'm not fluent in old tire sizes. Obviously they are 15", but I'm used to looking at radial tire sizing.
A little googling says that provided you can handle an extra inch of width without clearance issues, a 225/75R15 will be a close replacement (slightly wider, not quite as tall). Load rating should be at least as high or higher on that size too.
These are the exact tires that are on the trailer now:
http://www.easternmarine.com/loadstar-lt-7-00-15-heavy-duty-tire-load-range-e
7.00 is a 7" wide tread the rest of the numbers should say how many ply's there are you want 6 to 8 ply TRAILER tires (harbor freight), (tractor supply),not raidials.
anything in the 205-75 to 225-75 range will work. the 205's are very common and cheap. i just had a pair delivered for my cargo trailer for around $82 shipped for both from tires-easy.com
In reply to GTXVette:
There are plenty of radial trailer tires out there too. And they make for a nicer pulling trailer than the old-school bias-ply tires do.
Also, using an LT tire on a trailer is acceptable practice, although there's some load de-rating factor applied (can't remember what it is off-hand). An ST tire (trailer tire) is probably all you'll find for a 205/75 or 225/75 though. P-rated car tires are a no-go for a trailer.
While on the subject, what IS the difference between an ST and a car/truck tire?
The only thing I was ever able to find out was some mumblings about "lateral stability", which doesn't pass the BS-o-meter without further information. Cars and trucks need lateral stability too.
your right but the non-radial tire is designed with a stiffer side wall and I feel is better for trailering.10 ply is fine if you are moving heavy Eqip.6-8 ply is good for a car.
trailer tires have softer sidewalls then truck tires, they're made to act as the suspension.
In reply to Dietcoke:
I don't think that is correct. Trailer tires generally have a stiffer sidewall to reduce trailer sway and to deal with the lateral loads of turning a tandem axle trailer.
You may also want to keep in mind that most ST tires are only rated to 65 mph. If you do a lot of interstate towing, LTs would be a better choice. They are speed rated to 106 mph.
Toyman01 wrote: In reply to Dietcoke: You may also want to keep in mind that most ST tires are only rated to 65 mph. If you do a lot of interstate towing, LTs would be a better choice. They are speed rated to 106 mph.
Especially if you can run a size where an LT with some de-rate to its load rating is still plenty for your trailer. For a given size, the ST tire will often have a higher load rating, but unless you're already running a load range E ST with nothing higher available in LT and no room to fit a bigger tire, it shouldn't be an issue to find an appropriate LT.
Tires like the 7:00x15 had a higher aspect ration than todays tires. Something like 80% or so.
Well I'm planning on hauling cars on this trailer, so I'm probably going to stick with LT tires.
That is one stout trailer!
It looks like you could haul bulldozers on that thing.
Toyman01 wrote: You may also want to keep in mind that most ST tires are only rated to 65 mph. If you do a lot of interstate towing, LTs would be a better choice. They are speed rated to 106 mph.
Well, probably technically you shouldn't be towing a trailer that fast anyway.
That said, I wonder what HF trailer tires would be rated for. I've had them at 75+ for hours at a time, and exceeded 100 for a few moments a time or two.
In my driveway, of course, not on public roads...
Knurled wrote:Toyman01 wrote: You may also want to keep in mind that most ST tires are only rated to 65 mph. If you do a lot of interstate towing, LTs would be a better choice. They are speed rated to 106 mph.Well, probably technically you shouldn't be towing a trailer that fast anyway. That said, I wonder what HF trailer tires would be rated for. I've had them at 75+ for hours at a time, and exceeded 100 for a few moments a time or two. In my driveway, of course, not on public roads...
I figure that speed rating are set at maximum load. Reduce the load, increase the speed. I plead the 5th on any speeds my trailers have reached. Lets just leave it at fast. 
Any ST tire is only rated to 65. But if you're well below their maximum load, you'll be able to go somewhat faster without issue (there's just no way to really know what the limit is).
1988RedT2 wrote: That is one stout trailer!
Well it is an equipment trailer. It was my grandfathers and he hauled the tractor or trees and loads of dirt on it. After he passed, my uncle used it to transport cars on it.
I talked about it in my build thread, but this trailer needs some TLC. Tires and wiring for sure, but it needs the bearings gone through and a coat of paint. Deck boards are solid for being 25 years old.
Knurled wrote: While on the subject, what IS the difference between an ST and a car/truck tire?
Here's how it was explained to me.
First of all, there are completely different sets of parameters that can be eliminated when designing a trailer tire. Noise and ride harshness are less of a concern since you won't have passengers in the trailer to complain. Traction needs are completely different. Since the trailer does little braking and doesn't need to carve corners, the tread design and rubber compounds are different. They need to have fair lateral traction for emergency maneuvers but never have to handle torque application from driven wheels like a vehicle does.
You'll also notice that within a given size, a trailer tire tends to be rated for much more weight. Because you don't have to engineer a trailer tire to have a nice soft ride for grandma, you can make beefy sidewalls and tread plies that can handle more pressure and therefore more weight. Think of it this way; its easy to find a 205/70-15 ST in D-range with a max PSI of 60. Try finding a 205/70-15 LT tire that is more than 44 psi and can handle anywhere near that weight. It doesn't exist.
The primary difference I'm outlining is pressure capacity. An E-range tire doesn't handle more weight because it has stiffer sidewalls, it handles more weight because the stiffer sidewalls are a by-product of thicker/stronger sidewalls that can handle more pressure. Its not the stiff sidewalls that take the weight, its the air pressure that takes the weight. Its simply that (in order to handle the pressure) a heavy-duty tire has to have stronger sidewalls which happen to be stiffer. A vehicle is suspended by the air pressure in the tires, not the tire itself. Its the same reason why you never use the max pressure on the sidewall to inflate your tires, rather you use the sticker on the door jamb. You can put E-range tires on a Camry, but that doesn't mean it needs 80 psi. But, if you wanted to load that Camry to 9000 lbs (please don't), the E-range tires mean it is capable of holding the psi necessary to float that much weight without deflection and heat failure.
In short, trailer tires are made to hold big air in small spaces (carry more weight for their size), don't care about torque forces as much (accel/decel), don't care about longitudinal friction as much, and generally would suck as car tires.
One last (big) difference: ST tires (since they don't have to worry as much about friction) are usually made with a more UV resistant rubber blend. Usually in a vehicle you run out of tread before they dry rot. With a trailer, it might only see 1000 miles a year.
There is technically no reason not to use LT tires on a trailer, but you may have trouble finding LT tires in a weight capacity that suits the trailer. I understand that you might only be carrying X lbs of weight and don't need the extra weight capacity, but I usually suggest ST tires for three reasons: 1) A little bit more UV resistance, 2) why take an 8000 gvw trailer and cripple it by only putting 5000 lbs of tire capacity under it? 3) trailer tires are usually cheaper than LTs.
I remember I got a flat in my 31' travel trailer and my spare was toast. I found a shop with a 225/70-15 LT that I figured would be OK as a spare and would get me through for the rest of the trip. I was so wrong. Despite being the same size, it was pathetically not up to the task. It looked like it was half inflated even though it was at its max PSI. Everyone who passed me kept honking the horn and pointing like I was going to die. It made it about 300 miles before exploding into tiny shreds. A cop pulled over to check on me and asked me to make sure I dispose of the old tire and not leave it on the highway. Then I pointed to the carnage and he laughed and said "Ok, forget I said that."
Trailer tires belong on trailers. Passenger tires do not. Up to you, but I would not use LT tires on a trailer.
^^ all of this.
You can theoretically use a hammer to drive in a screw, but there's a better tool for the job.
That having been said, you can still choose between bias-ply and radial-ply trailer tires. Dollar for dollar, you'll get a higher load rating for a bias tire than for a radial.
Example: For $80, you can get a Load Range D bias-ply tire or a Load Range C radial in your size (Roughly a 205/75-15). Or you can pay $100 and get a Load Range D radial. You pays your money and you takes your choice.
LTs are often better made than trailer tires, however. Keep in mind, basically every trailer tire on the market comes from China at this point (even the Goodyears).
The load capacity thing is a very good point. STs do carry more weight for a given size. On some trailers, that limits you to only running STs, as an LT of any size that fits the trailer would be maxed out by the time you hit GVWR on the trailer.
On others, the max GVWR of the trailer would put the tire loading very far below what's available in a size that'll fit the trailer. In those cases, giving up some weight capacity to run an LT is fine, as you'd still have plenty of headroom. Also, if it came with load range C STs, a load range E LT of the same size will likely carry as much or more weight.
For 15s, there's usually not much in LT choices anyway, so you're probably going to end up with STs. 16" wheels are where the ST / LT debate becomes more relevant.
You guys realize that there are LT Trailer Tires right?
I've been researching the 7.00-15 which there are not a ton of, but there are Bias Ply LT Trailer tires that are available.
If ST tires will work for a trailer like mine, I will consider them. The LT trailer tires are still a little more than I want to pay.
curtis73 wrote: I remember I got a flat in my 31' travel trailer and my spare was toast. I found a shop with a 225/70-15 LT that I figured would be OK as a spare and would get me through for the rest of the trip. I was so wrong. Despite being the same size, it was pathetically not up to the task. It looked like it was half inflated even though it was at its max PSI. Everyone who passed me kept honking the horn and pointing like I was going to die. It made it about 300 miles before exploding into tiny shreds. A cop pulled over to check on me and asked me to make sure I dispose of the old tire and not leave it on the highway. Then I pointed to the carnage and he laughed and said "Ok, forget I said that."
I am confused. Every set of LT tires I have had had a max inflation of 80 PSI. It sounds like you had an LT tire at 40 PSI. The last time I had a tire shop install some used LT tires on my truck they sent me out with the tires at 33 PSI. It felt like I had 4 flats.
Personally I am going to put passenger tires on my trailer, but I am not going to haul more than 500 pounds.
Ok, so after some more research, I'm pretty sure I have 5.5 inch rims. So without having to buy new rims, I'm going to need 205-75R15 Size tires. Everything I read is that 225 need a 6" or wider rim. I found some decent ST tires on Amazon for a good price.
I found these: http://amzn.com/B01CLS0DQ4
Seems like a decent deal.
OH Man, I haven't seen one of those since I quit changing tires at my Grandpa's tire shop in the mid-70's. 7.00-15 was the size on a lot of the pickup trucks back then. The "LT" just meant Light Truck. Most of these were called 6 ply This is the old bias tire construction.
Originally a ply was a layer of cotton fabric vulcanized into the tire to hold it together much like the fiber in fiberglass. The more cotton plys the higher the load rating. Later, when nylon and rayon and then aramid fibers came along, which was much stronger than cotton, they would use fewer actual plys but, since everyone knew the load ratings by the original cotton ply's capacity, they just kept calling them by the load rating capacity of the plys of the old cotton ply standard.
For your replacements just look up the "revolutions per mile" of the 7.00-15LT and buy a tire with approximately equal "revolutions per mile" and that can handle those narrow rims. Diameter is not as exact because radial tires have more flex in the sidewalls so the loaded radius is less with equal diameter to the bias ply tire. Alternately you could possibly find this actual size in a modern radial truck tire from one of the major manufacturers - if you do that you have a better chance of the side walls not rubbing the trailer fenders.
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