# Trailer tire size



## Curtis B (Aug 15, 2008)

I just bought a two horse trailer, and it needs a two new tires. The two tires that need replacing are toast, and smaller than the other two that are fine. The good ones are a 135-15, and I can't tell on the other small ones other than 15" rims. I would get 135's, but they look tight in the wells, and I would hate for them to rub when it is loaded. Is there a standard size? I can get some pics if I need to. The person I got it from didn't know, he recieved it for payment on a loan from a guy he knew.


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## oneokie (Aug 14, 2009)

Curtis B said:


> I just bought a two horse trailer, and it needs a two new tires. The two tires that need replacing are toast, and smaller than the other two that are fine. The good ones are a 135-15, and I can't tell on the other small ones other than 15" rims. I would get 135's, but they look tight in the wells, and I would hate for them to rub when it is loaded. Is there a standard size? I can get some pics if I need to. The person I got it from didn't know, he recieved it for payment on a loan from a guy he knew.


Is that a typo? Most radial trailer tires I have seen are 205's or 215's.


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## Curtis B (Aug 15, 2008)

No typo, brain fart. You are correct, they are a 235's, and smaller. My thought was all four were bad, and two used ones were put on, and 235 was all he could find for a 15" rim.


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## agmantoo (May 23, 2003)

Used 15 inch tires are scarce in the 235 range. At one time they were plentiful as that is what was used on stock Ford pickups before they increased the rim size. I have a lot of farm equipment that need the 15 inch tires and I have had to revert to buying new tires in order to get the size. I would want very reliable tires in the correct load range on a trailer used on the highway.


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## haypoint (Oct 4, 2006)

Horse trailer tires take a lot of abuse. Generally they sit most of the time, but when they are used, they carry heavy loads and often high speeds. Easy for a decade to slip by and forget you have nice tread, but out of date tires.

Check the load rating on those tires and do the math. I was ready to buy a heavy steel 4 draft horse gooseneck but the tires were rated for 1750 pounds! Someons switched tires when they traded it in. I did get the seller to put new rims and heavy dury tires on it.

There is another number you also need to be looking at. It is between the 235 and the 15. Some 235 15's are taller than others. 60, 70, 78, etc.


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## Fat Charlie (Sep 9, 2010)

235/XX/15. 235 is the width, 50, 55, 60, etc. is the "aspect" and 15 is the rim size. The aspect is the size of the sidewall as a percentage of the tire width. In a 235/60/15, the tread is 235mm wide, the sidewall is 141mm high (60% of 235mm) and it goes on a 15" rim. On a trailer, you don't really need to worry about it. If the tires have the right load rating and fit, you should be good. 

I just looked back and saw that you've got four tires total- keep them all the same size. If you can score a full set of a slightly different tire size, use that full set.


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## haypoint (Oct 4, 2006)

OP stated, "but they look tight in the wells." The Aspect ratio effects that clearance. A 235/60-15 will be shorter, more clearance, than a 235/78-15. When sorting through used tires, that middle number should be a concern.


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## Drizler (Jun 16, 2002)

I feel your pain. We did the same thing last year with our horse trailer and wound up tossing out 2 very good biaz 235 15 tires for no other reason than inavailability. We ended up with 4 Carlisle radials and found out they were made in China. I keep them covered all the time with tarps. Chinese tires are ----, PERIOD no matter who makes them. When I got my boat trailer tires I got the bias Carlisle's as they are made in the USA. No flag waving here but a simple statement of fact, Chinese tires of any make will weather check in no time. I just tossed a set of old tires from the boat trailer 20 years old and though cracked they held up for 20 years . You won't see that from a new Goodyear and they are ----ed expensive.
The real thing today is that you can't get a decent reasonably priced trailer tire. They just don't make any. You can save a few bucks by using your old rims rather than buying complete wheels though it's hard to do that even with a horse trailer as most have those cheap painted rims that love to rust.


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## Beeman (Dec 29, 2002)

Buy trailer specific tires, not passenger car tires. Most likely need 205/75/15, about $75 each.


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## Curtis B (Aug 15, 2008)

There might be a bit of terminology difference here. I allways thought of the first number (say 235) as the "height/dia" of the tire, same as a "35" is aprox 34.5" tall. The second number was the width (60), and the last 15, was a 15" dia rim. My thinking was maybe replacing all with a 215, which would be slightly smaller in the well, as far a clearance from the top of the tire to the underside of the fender. What I am looking at is not knowing how much sag the springs will have, and under load rubbing on the underside of the wheel well.


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## oneokie (Aug 14, 2009)

Curtis B said:


> There might be a bit of terminology difference here. I allways thought of the first number (say 235) as the "height/dia" of the tire, same as a "35" is aprox 34.5" tall. The second number was the width (60), and the last 15, was a 15" dia rim. My thinking was maybe replacing all with a 215, which would be slightly smaller in the well, as far a clearance from the top of the tire to the underside of the fender. What I am looking at is not knowing how much sag the springs will have, and under load rubbing on the underside of the wheel well.


Fat Charlie gave the correct definition of how radial tires are sized.

The second number is what determines overall tire diameter. Example: A 235 tire with the second number of 78 would be the tallest tire. If the second number was 75, it would be shorter, a 70 would be even shorter and so on as the second number decreases, staying with the same rim diameter.


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## Old Vet (Oct 15, 2006)

If you get car tires try to get LT tires. The LT tires are much heaver and will carry more than regular passenger tires will.


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## Drizler (Jun 16, 2002)

Curtis B said:


> I just bought a two horse trailer, and it needs a two new tires. The two tires that need replacing are toast, and smaller than the other two that are fine. The good ones are a 135-15, and I can't tell on the other small ones other than 15" rims. I would get 135's, but they look tight in the wells, and I would hate for them to rub when it is loaded. Is there a standard size? I can get some pics if I need to. The person I got it from didn't know, he recieved it for payment on a loan from a guy he knew.


FWIW the tires I have now 225's as well as the old bias 235's did and do fit real tight on our trailer. They don't seem to have any problem and it;s an 89 so if they were gonna hit it would have happened by now. Too bad you have those lousey 235's as it's near impossible to match anything up to fit other than replacing them all like I did. Check out the online tire stores chat sections or call them. The last 2 sets of tires I got were from tireseasy.com No great web site ect but with shipping theirs were cheaper than anyone else. I hear a lot of guys are going to LT truck tires lately instead of ST trailers for reliability / durability reasons. I would myself in a minute for a lighter use than a horse rig. For that much weight it makes me skeptical. Probably the best thing to do is keep the speed down under 65. Flyin low hauling a heavy trailer creeps me out and makes the tires a lot hotter.


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## Old Vet (Oct 15, 2006)

Drizler said:


> FWIW the tires I have now 225's as well as the old bias 235's did and do fit real tight on our trailer. They don't seem to have any problem and it;s an 89 so if they were gonna hit it would have happened by now. Too bad you have those lousey 235's as it's near impossible to match anything up to fit other than replacing them all like I did. Check out the online tire stores chat sections or call them. The last 2 sets of tires I got were from tireseasy.com No great web site ect but with shipping theirs were cheaper than anyone else. I hear a lot of guys are going to LT truck tires lately instead of ST trailers for reliability / durability reasons. I would myself in a minute for a lighter use than a horse rig. For that much weight it makes me skeptical. Probably the best thing to do is keep the speed down under 65. Flyin low hauling a heavy trailer creeps me out and makes the tires a lot hotter.



A load range E tires in the LT will have more load that even ST tires or least as much.


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