Tractor Sizing YM165D Turf Tire size

gt14 · Jan 9, 2007

What is the equivalent turf tire that will fit an YM165D for both front and back wheels? I have heard I need to make sure tire sizes have a certain ratio so the 4WD doesn't work against itself. I have also heard that I may need new wheel rims for the turf tires. Any info?

John_R · Jan 9, 2007

gt14,

Since the YM165D is a US model then it probably had the option of turf tires for it when originally sold. If this was an option then the operators manual for it should list the recommended sizes for the turf tires. Most likely you will have to replace your current wheels because the R3 Turf tires will be to wide for the rims that your R1 Ag tires are mounted on.

If the YM165D didn't originally have turf tires as an option then you have to do it the hard way and figure out the information yourself. In this case the important factor you have to take into consideration for tire sizes on a MFWD tractor is the lead/lag percentage of the front to rear tires. A good explanation of and examples on how to calculate this number can be found on this Titan Tire web site file http://www.titanstore.com/pdf/TireInfo.pdf. Page down in this document until you find the section titled 'Rolling Circumference'. The lead/lag percentage for Yanmar tractors needs to be in the range of positive 0% to 6%.

To calculate the lead/lag percentage number you will need to know the front-to-rear gear ratio of your tractor. Since you have a US market Yanmar you should be able to find this in the Yanmar service manual for the tractor in the 'Power Train Operation and Tests section'. In the YM276D manual that I have, this number is referred to as the 'Front Axle-to-Rear Axle Speed Ratio'. If you don't have a service manual for your tractor then you can measure the front-to-rear gear ratio. That is what I had to do for my YM2310D. It's not particularly difficult to do.

With the front to rear gear ratio number in hand you can then look on the Titan or Firestone Agricultural tire sites for front/rear R3 turf tires that will physically fit on your tractor and that have the proper rolling circumferences which will maintain the desired lead percentage number. Once you've chosen some tires then you need to find existing wheels to fit them or have custom ones made. Or you can start with the wheels first and then find tires to fit them that meet the desired criteria. This can be a lengthy iterative process.

HTH.

John_R

gt14 · Jan 10, 2007

Thanks I looked in the book and it gave me some info as you described. My front tires are 6-12 I don't know what these numbers mean but I assume the numbers refer to rim diameter and rim width, Since the tires don't measure with a ruler to be 12" or 6" I think they are ~21" tall and ~7.5" wide.
The rear tires are 4ply 8-16. So I will keep looking. These tires really tear things up, I made 10 or so trips from a tree I cut down to my wood pile and it made huge ruts.

SailorBob · Jan 10, 2007

gt14 said:
These tires really tear things up, I made 10 or so trips from a tree I cut down to my wood pile and it made huge ruts.

I don't know if your tires are like the rice tires that a lot of us have but, there is a guy here who took a saws all and trimmed down to lugs on the tires. It looked really nice. I have been thinking about doing the same thing.

Mickey_Fx · Jan 10, 2007

gt14 said:
Thanks I looked in the book and it gave me some info as you described. My front tires are 6-12 I don't know what these numbers mean but I assume the numbers refer to rim diameter and rim width, Since the tires don't measure with a ruler to be 12" or 6" I think they are ~21" tall and ~7.5" wide.
The rear tires are 4ply 8-16. So I will keep looking. These tires really tear things up, I made 10 or so trips from a tree I cut down to my wood pile and it made huge ruts.

GT, go the the Titan web site as there is a lot of good info there. Look up your stk tires and you should find info on dia and rolling circumferance. From that you can determine ratio of front to back and then find another combination (size and tread pattern) with very close to the same ratio. Did that for mine recently. Need to watch for rec rim width.

6x12 = 6" wide (at tread ?) by 12" rim dia.

You might want to drop in to Les Schwab as they carry a lot of tractor tires and might be able to help you out.

John_R · Jan 10, 2007

gt14,

To satisfy my curiosity, since I've not been interested in turf tires myself, I checked to see if there are any direct replacement turf tires for the tire sizes that are on your tractor and surprisingly enough Firestone makes some. I have provided links to the turf tire web pages and to an Ag tire web page for comparison purposes. Once a page opens click on the 'View Dimensions & Loads' button. This will open up a new window with lots of detailed information on all of the sizes available for that tire style.

I compared the 'rolling circumference' numbers for your size tire between the R-1 Ag and R-3/G-2 tires and the rears are exactly the same. The fronts have a small difference between them with the turf tire having a slightly smaller 'rolling circumference' but this may be acceptable. This is where the knowing the front-to-rear gear ratio is important so that you can calculate the lead percentage. Smaller rolling circumference numbers on the front tire for a given front-to-rear gear ratio move the lead percentage closer to 0% and can, if the difference is great enough, create a lag percentage number which is undesirable.

What Mickey_Fx said regarding your 6x12 tire is exactly what the 6 and 12 numbers mean. Elaborating on the rim measurements some, rim width is measured between the bead flanges (inside to inside) and the rim diameter is measured bead seat to bead seat. Since the bead seat/flange are the part of the rim that the tire seats to they are difficult to measure with a mounted tire. This is why your rim diameter measurements don't make sense.

The 6x12 tire size has one acceptable rim profile regardless of tire style and that is 5JA. The 8x16 tire size has three acceptable rim profiles regardless of tire style and they are, 6.00F, 6LB, or 6L. The rim profile number is usually stamped somewhere on the rim itself along with the manufacturers initials, country and a date code. The rim width is the number part of the rim contour designation.

More tire information to ponder.

John_R

R-3 / G-2 (turf) tires
Firestone Agricultural Tire Division : Tire Details (front)
Firestone Agricultural Tire Division : Tire Details (rear)

R-1 Ag tires for comparison
Firestone Agricultural Tire Division : Tire Details (front and rear)

gt14 · Jan 27, 2007

Has anyone ever mounted Wide Truck Tires onto a smaller yanmar? My chevy 1500 truck tires are the same height. Maybee I could even use truck rims. I would probably mount 295-325 mm wide tires. That should be about 11.5" to 13" wide. I would find used tires not buy new to save$.

buppy69 · Jan 28, 2007

I know of a lot of people who have used truck tires on smaller tractors. On mine, I just measured the diameter of the ag tires and bought the same diameter of turf tires and rims. They work great and no math!

Eugene