Tractor Sizing Yanmar 186D front tyre sizes

Yanmar186d · Jul 30, 2015

Hi i have just purchased a set of front tyres for my yanmar tractor, the tyre size is 6-12 but I noticed that I've been sold a tyre that is 6.00 12, I made a note to the guy and he said its the same tyre but they appear to be a taller tyre, can I run this tyre or will it cause me issues? Thanks for any advice cheers.

Neat 1500 · Jul 30, 2015

Hello fellow Melbournian, How much taller is it? I know with the "D" models you have a very small window for tyre ratio difference. Only use it on soft ground and never on hard surfaces. One of the others will chime in and give you a calculation you can do to see if it is OK.

winston1 · Jul 30, 2015

Take a look at this. Two New 6 00 12 Duro Tractor Tires Tubes Real 6 00 12 Bigger Than 6 12'S | eBay

Yanmar186d · Jul 30, 2015

So going by the link winston has added the 6.00-12 tyre is 2 inches taller than the 6-12,from the centre of the rim to the ground that would make the tyre 1 inch bigger compared to the 6-12 tyre? Is this going to be a problem considering a new tyre has over an inch of lug and when that wears down it loses close to an inch of height from centre of the rim to ground if that makes sense. If I was to use these on the dirt in 4WD will they be ok, I could disengage the 4WD on concrete if it was going to cause an issue.

Yanmar186d · Jul 30, 2015

Also as I'm running a loader I want a 6 ply tyre but 6-12 are 4 ply and seem hard to find in 6 ply.

winston1 · Jul 30, 2015

2 inches difference in diameter amounts to over 6" in circumference. Not my call, but that is a lot of difference. Here are 6 ply 6-12s. 6-12 Carlisle Farm Specialist Farm Tractor Tire (6 Ply) (TL) same dealer has the 6.00-12s in 6 ply. 6.00-12 BKT TR-171 Deep Tread Farm Tractor Tire (6 Ply) (TT)

old grayfellow · Jul 30, 2015

Yanmar186d said:
Hi i have just purchased a set of front tyres for my yanmar tractor, the tyre size is 6-12 but I noticed that I've been sold a tyre that is 6.00 12, I made a note to the guy and he said its the same tyre but they appear to be a taller tyre, can I run this tyre or will it cause me issues? Thanks for any advice cheers.

Think California on this forum has the same situation on one of his 186D's.

California · Jul 30, 2015

Its not acceptable to run a 6:00x12 in place of 6-12.

As Winston said, 6:00x12 has 6 inches larger circumference. At each revolution of the front tires, the front of the tractor tries to move forward 6 inches greater distance than the rear tires move forward. Tire slip - skid - is the only way the tractor can move at all. This mismatch will destroy driveline components.

Particularly with weight in the loader, both the front and back of the tractor have good traction so the stresses are huge.

That said, I'm running that mismatch temporarily on the YM186D that I use all the time - but I never engage the front axle unless the back tires are slipping, or when my safety on sloped ground is more important. I put on some used 6:00x12's until I can get around to buying the proper 6-12's. And I worry about it every minute I use 4x4.

Photo last week, watering new trees. There's so much weight on the rear hitch that the front end is light. 4x4 is needed for safety driving down the slope, and for turning here instead of plowing straight ahead. The water level in the tank is level, for reference.

Yanmar186d · Jul 30, 2015

Thanks for your help guys tyres have been returned and the right size sourced.

Yanmar186d · Jul 31, 2015

normde2001 · Aug 1, 2015

winston1 said:
Take a look at this. Two New 6 00 12 Duro Tractor Tires Tubes Real 6 00 12 Bigger Than 6 12'S | eBay

Always wondered, what does the 6 represent in 6-12 or 6.00-12? Apparently has very little to do with 6".

California · Aug 1, 2015

I think the 6 is the tire casing width, which is important for some applications such as fitting in an automobile fender or running truck duals.

Then the 80-70-60 etc portion of modern tire specs is the proportion of height to this width number.

normde2001 · Aug 3, 2015

California said:
I think the 6 is the tire casing width, which is important for some applications such as fitting in an automobile fender or running truck duals.

Then the 80-70-60 etc portion of modern tire specs is the proportion of height to this width number.

So what does 6.00 mean, as opposed to 6?

California · Aug 3, 2015

Who knows? An hour on Google might resolve it. I'm not going to bother.

normde2001 · Aug 4, 2015

California said:
Who knows? An hour on Google might resolve it. I'm not going to bother.

As I suspected:confused3:

California · Aug 4, 2015

normde2001 said:
As I suspected:confused3:

What did you suspect, Norm?

California · Aug 4, 2015

Not that this is going to shed any light on the difference ...

I just went out and measured the tire width on the two YM186D's.

6" casing, 7" tread: tire designated 6-12.
6 7/8 casing, 6 1/2 tread: tire label 6.00 x 12.

Both have deeper lugs than the photos I see on Ebay.

And I have a question if anybody's still reading this thread: I see 6-12 r-1's in 4 ply and 6 ply on ebay. Clearly 6 ply is rated to stand up better to continual loader use but is there any practical difference if the loader seldom has much weight in it? Seems to me the more flexible 4 ply would have better traction and therefor is preferable for general use. Has anybody ever burst one of these small tires carrying something heavy?

California · Aug 18, 2015

Maybe somebody can use this info in the future.

I found an old photo I took of a 6.00 x 12 (the taller tire) and a 6-12 (the size Yanmar specifies for YM186D).