reading tire sizes

[thatguy]

OK, someone help me out here...

What does the tire size 26X12-12 or 26x12.00-12 mean? which is width? diameter? radius?

thanks

brian

 

[73jeep]

26 x 12.00 - 12

The 26 = overall tire height in inches.
The 1st 12.00 = overall tire width in inches.
The 2nd 12 = The wheel-rim diameter in inches.

 

[thatguy]

thank you

b

 

[rk246]

Okay so on the 3830 14.9 X 24?

 

[ZJ_HR]

14.9-24 equal to old way of marking 14.9/13-24

14.9" is width of tire, 13" is height of tire, and 24" is rim diameter.
So, total height of tire will be 50", and according to new designation, your tire will "sound" 50x14.9-24.
Here in Europe every day are more common metric size tires, with similar designation as car tires.

 

[daTeacha]

So is there a move toward a uniform sizing system for tires on these things? I remember when car tires had letters for width and the rim size. Then there was a letter and a number for aspect ratio and the rim size. Now there is a width, aspect ratio, rim size, speed rating and load rating at speed plus the load range.

 

[ZJ_HR]

Personally, I like milimeter measured tires more, maybe because we use metric system here.
All metric sized tractor tires are radials, when inch sized can be ether radials or cross ply (bias).
Seems that all is in history and habbits. Here tractors use wide, low profile radials when there are more common normal bias tires mounted as duals.

On my smaller tractor there are 8.3/8-20 and 12.4-28, when on bigger one are 360/70-20 and 420/70-30.
Problem is that there are no that small metric sized tires for older tractor.

 

[rk246]

Thanks, can you tell me what the formula is to figure out the tire size? My truck used to have 35 x 12.50's x 16.5's that was easy, 35 inches high 12.5 inches wide, now it has 315 x 75's x 20's, now I know that 20 is the rim size but I don't get the rest of it, and the tractor size thing really threw me off, How do you know that it is 14.9 x 13? I can understand the 24" thing for the rim, but the rest doesn't make sense to me?

Thanks

 

[ZJ_HR]

Read some manufacturers tire size charts. And we have lot older tractors here; some of them have 14.9/13-28 and some just 14.9-28. Both tires are equal in height. Tire dimensions are not changed just a designation. Just few sizes, for example, which have similar diameter/circumference:

old des. ....... new des. ... similar metric ... low profile metric
11.2/10-24 ... 11.2-24 ... 280/85-24 ... 320/70-24
12.4/11-24 ... 12.4-24 ... 320/85-24 ... 360/70-24
14.9/13-28 ... 14.9-28 ... 380/85-28 ... 420/70-28
16.9/14-28 ... 16.9-28 ... 420/85-28 ... 480/70-28

Just for example, rims are 24 and 28", can be 20, or 30" or ...

You mentioned 35x12.50x16.5, or other (tractor like) designation will be 12.5/9.25-16.5.
Metric ones 315/75-20 are 12.4" wide, 9.3" high, but 20" rim seems too big, as this wheel will have 38.6" diameter, which is higher then old 35", except if you notice bigger tires and higher vehicle.

 

[daTeacha]

This should be simple, but it's pretty confusing. Kubota offers an Ag tire as standard on the L3400. The size is 11.2 -- 24. They also offer an industrial tire for the same tractor in size 15 -- 19.5. Now I understand that the last number is the rim size. The turf tire size is 13.6 -- 16. For the industrial and turf option, they give an overall height for the front tires, but not the rears. R4 front is 27X8.5 -- 15 and for turf the fronts are 25X8.5 --14. In the size system for the rears, is the first number the width or the height of the tire? If it's the width, how do I figure out the overall height for the optional tires?

Regarding small metric tractor tires, it would seem that the Japanese tractors should have metric size tires in their home market. Maybe you could find a source there in Europe that can get them direct from the factory??