What do tractor tire chain numbers mean ?

Hodgy

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What do tractor tire chain numbers mean ? Is there any way to tell what the width and length of the chains are from the chain number ?

I am looking for used tire chains for the B7800 and have one set for sale but the owner has them in storage and can't get to them. She has a photo of the original box they came in with the JD part number and chain size.

JD 7807-133-77 and the chain size is 31 x 12.5 x 15.

Help !





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Roadworthy

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Well, those are too big for your Kubota. If I read them correctly (and I could be wrong) those are for a tractor with a 31 inch wheel about 12.5 inches across which kind of tells what size tire it uses. I suspect the 15 refers to the number of cross links between the inner and outer chain.
 

North Idaho Wolfman

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Roadworthy your a little off. ;)

The chain size is the same as the tire size.

They might fit your tires on your b7800 I'd have to look it up, they are 31" in circumference, 12.5 in width and 15" rim.
 
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Hodgy

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Thanks for the responses. If the chains are to long that's OK, I can cut. its the width that I worry about. I need chains that are 18" wide at least and 120" in circumference.

I have looked for a chart to see what the numbers mean and can't find one.


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Hodgy

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I believe that the 31 is the diameter of the tire.

31' diameter would work for me. I need a tire chain guru to explain what the numbers on chains mean.

Or better yet the seller to go and measure the chains and let me know. She only wants $75 for the set. I think I will just offer her $50 and pick them up. If I can't use them I will sell them. Better than the $500 I was quoted for the correct size "H" chains.

She gave me some more information that they were on a John Deere 4010 which is a 80 HP tractor, tractor data shows 38" tires. So they will be long enough, just not sure about the width.

Will post again once I get the chains.

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D2Cat

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According to Tractor Data this is the size of the rear tires on a JD 4010 13.6 x 38, as you stated. You'll surely have enough chain, just need to modify it. But for $50-75 you can save a bunch of money. You'll have to shorten and narrow the chains.

You could probably use a set of chains for a pickup truck with 16" tires. That's what I use on a B6100. Still have them hanging on the wall.
 
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tthorkil

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According to https://www.tacomaworld.com/tirecalc?tires=275-75r15-31-12.5r15 :
Tire size 31/12.5-15 has the following characteristics:
Diameter inches (mm) 31.03 (788.04)
Width inches (mm) 12.52 (318)
Circum. inches (mm) 97.47 (2475.7)
Sidewall Height inches (mm) 8.01 (203.52)
Revolutions per mile (km) 650.06 (403.93)

If the chains were used on a John Deere 4010 they must have been on the front tires(Ag front: 6.00-16).

John Deere 4010 Ag Rear:
13.6-38 Firestone
Overall Width: 13.6 Inches
Overall Diameter: 61.5 Inches
Rolling Circumference: 184 Inches
 

BigG

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According to Tractor Data the 4010 has rear tires 29x12.50-15.
 

tthorkil

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Tire sizes seem to be more complicated than I originally thought - I just found a site that explains Lawn Tractor tire sizes - https://www.tires-easy.com/blog/lawn-tractor-tires-sizing-buying-guide/

1. Lawn Tractor Tires Sizing
Like any other tire, lawn tractor tires have a series of numbers molded on to the side that spell out specific details about the tire. There are two different sizing systems: two-number system, and three-number system.

Two-number Tire Sizing
Lawn tractor tires using the two-number system display numbers as 4.80-8, for example. This means the tire’s width is approximately 4.8 inches and the rim is 8 inches in diameter. Those are the only two numbers you need to find the right size replacement tire.

Three-number Tire Sizing
The three-number lawn tractor tires numbering system works a bit differently. 15×6.00-6 is a common size. The first number before the “x” indicates the tire’s diameter when inflated and not under load. The middle number between the “x” and the “-,” indicates the tire’s width. The final number indicates the width of the rim. Note that the last number is width, not diameter of the rim. This is always the case with three-number sizing for lawn tractor tires and other garden equipment tires.
 

billfires

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Just a correction. The third number is the diameter. Example is 15-6.00-6 and 16-6.50-8 on Wheel Horse tractors. It is not possible to put a 6.50 wide tire on an 8 inch wide rim. That website is incorrect. Bill C
 
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