Tire Question - New Tires - B7200 - Can't Find Answer

[ttj49]

I searched through the forums but couldn't find the answer. I'm going to replace the front and rear tires on the 'ol B7200. The front is not a problem. They are 6 - 12 and easily found.

The current size on the rear is 9.5 - 16 and they are not so easily found, and somewhat expensive. The 9.5 - 16 was a optional larger size upgrade for my tractor. Carlisle and a few imports are out there, but....

I can get the standard tire in an 8 - 16 size a lot cheaper and they are more readily available. My rims are 9 or 9.5 inches wide. Will the 8 -16 size mount on my current rims? Has anyone done this effectively?

BTW, these are all standard lug tires, which is what I want.

 

[North Idaho Wolfman]

No, normally you can not just change just the rear wheel size on a 4x4.
There is a ration that needs to be maintained in order for the front not to get damaged.

BUT!
You have the Wrong front tires on it right now.
It should have 5-10 fronts for the 9.5-16 rears
It should have 6-12 fronts for the 8-16 rears
I suspect that someone changed the rears out for the wider ones without changing the fronts.

 

[lsmurphy]

No, you cannot mount the 8x16 on the 9" wheel.

Carlisle Farm Specialist, $250 each.


Very good tires.

 

[lsmurphy]

BTW.........

Every change in width brings a change in diameter or RC (rolling circumference)

Fronts and rears must be matched.

 

[ctmike]

Here's a link to a Goodyear tractor tire web page that has more information than you'll ever be looking for, but there is a chart of rolling circumference of various sizes of tires.
http://www.titan-intl.com/files/Agriculture/Catalog_full_nocrops_reduced.pdf

 

[ttj49]

Thanks all....good info....

 

[ttj49]

No, normally you can not just change just the rear wheel size on a 4x4.
There is a ration that needs to be maintained in order for the front not to get damaged.

BUT!
You have the Wrong front tires on it right now.
It should have 5-10 fronts for the 9.5-16 rears
It should have 6-12 fronts for the 8-16 rears
I suspect that someone changed the rears out for the wider ones without changing the fronts.

View attachment 10274

Thanks to everyone for all of the good information. The fact that someone most likely switched the back wheels and tires brings up another question.

Will the 5.00-10 fit on the rims that are now holding the 6-12 tires? Or will I have to get different rims to accept the 5.00-10 tires?

Thanks......

Thanks.....

 

[North Idaho Wolfman]

They are different rims, they are 10" rims not 12" rims.

 

[Dan_R_42]

ctmike, thanks for sharing the link... Great info

 

[ttj49]

They are different rims, they are 10" rims not 12" rims.

Yeah, that's what I thought too... I just didn't want to hear it....

Thanks...

 

[lsmurphy]

The 5-10s are for 2WD.

The 6-12s are for 4WD.


Do you know what you have?



Sounds like you guys need to get more sleep.

 

[Rob]

Or....
Kubota B7200 Tires:
Standard tires (ag): Front: 5.00-10. Rear: 8-16 (2WD)

Front: 6-12. Rear: 8-16 (4WD)

Optional tires (ag): Front: 5.00-10. Rear: 9.5-16

Lawn/turf front: 18x9.50-8 (2WD)

20x8.00-10 (4WD)

Lawn/turf rear: 29x12.00-15

31x13.5-15

 

[tiredguy]

I searched through the forums but couldn't find the answer. I'm going to replace the front and rear tires on the 'ol B7200. The front is not a problem. They are 6 - 12 and easily found.

The current size on the rear is 9.5 - 16 and they are not so easily found, and somewhat expensive. The 9.5 - 16 was a optional larger size upgrade for my tractor. Carlisle and a few imports are out there, but....

I can get the standard tire in an 8 - 16 size a lot cheaper and they are more readily available. My rims are 9 or 9.5 inches wide. Will the 8 -16 size mount on my current rims? Has anyone done this effectively?

BTW, these are all standard lug tires, which is what I want.

No you can't just switch on a 4 wheel drive without causing major problems and after you fix it you'll have to buy new correct size tires anyway. Ismurphy is right on the money, Carlisle's the way to go all the way for the best value.

Did it come with the 6-12/9.5-16 combo? How long have you had the tractor, long enough to know if it binds up in 4 wheel drive? I believe it more than likely has the correct combo in it now but would contact a Kubota dealer and ask them if they know what's right. Since I know it doesn't use the 5-10 tire size ( I have never seen a tire that size ever on a Kubota or anything else by the way ) the only possibility "might" be the 20.5-8-10/21x800-10 Firestone Turf & Field tires which is as popular on a B7100 Kubota as the orange paint it's covered with from the factory.

I'll check my notes Monday and see if I have any on the B7200 and try and comment if I do then.
Al

 

[ka24deroadster]

No, normally you can not just change just the rear wheel size on a 4x4.
There is a ration that needs to be maintained in order for the front not to get damaged.

BUT!
You have the Wrong front tires on it right now.
It should have 5-10 fronts for the 9.5-16 rears
It should have 6-12 fronts for the 8-16 rears
I suspect that someone changed the rears out for the wider ones without changing the fronts.

View attachment 10274

I logged into this forum to see if i could get a definitive answer to when and how you could run 9.5-16 tires on the back of a b7200, and now i am more confused than when i started. Where did you get the information that the front tire need to be 5-10 for the 9.5-16 rears? I have not seen the specs for the 5-10 tires but i am guessing that they are shorter than the 6-12. If they are shorter, why would you pair them with the taller back tire? That would make the ratio even worse. I dug out my operators manual for my tractor and it only lists the 5-10 for 2-wheel drive models. Am I missing something here? I am purchasing some replacement tires (9.5-16) and want to make sure i am not going to screw thing up. Was there a different gear ratio if the tractor came with 9.5-16's? My tractor is 4-wheel drive. If it was 2-wheel drive ratios would not matter.

 

[85Hokie]

I logged into this forum to see if i could get a definitive answer to when and how you could run 9.5-16 tires on the back of a b7200, and now i am more confused than when i started. Where did you get the information that the front tire need to be 5-10 for the 9.5-16 rears? I have not seen the specs for the 5-10 tires but i am guessing that they are shorter than the 6-12. If they are shorter, why would you pair them with the taller back tire? That would make the ratio even worse. I dug out my operators manual for my tractor and it only lists the 5-10 for 2-wheel drive models. Am I missing something here? I am purchasing some replacement tires (9.5-16) and want to make sure i am not going to screw thing up. Was there a different gear ratio if the tractor came with 9.5-16's? My tractor is 4-wheel drive. If it was 2-wheel drive ratios would not matter.

try this site - notice the difference between 2wd and 4wd

http://www.tractordata.com/farm-tractors/001/2/7/1272-kubota-b7200-dimensions.html

 

[ka24deroadster]

try this site - notice the difference between 2wd and 4wd

http://www.tractordata.com/farm-tractors/001/2/7/1272-kubota-b7200-dimensions.html

I do notice the difference on the "Tractor Data" website. It is different than the data on the page from my factory Kubota owners manual. What information should i consider correct, the information supplied by my tractor manufacturer or the information supplied by a website? I would think that the factory that made the tractor would know what tires it could use. The factory owners manual only specs 6-12 farm(ag) fronts for a 4wd. There are no 5-10 farm front tires on 4wd tractors. What is the diameter of a 5-10 ag tire? i can not find how tall it is compared to the 6-12. If it is shorter then can you tell me why they would use it with taller rear tires? The ratio would would be worse with shorter front tires.

 

[85Hokie]

I do notice the difference on the "Tractor Data" website. It is different than the data on the page from my factory Kubota owners manual. What information should i consider correct, the information supplied by my tractor manufacturer or the information supplied by a website? I would think that the factory that made the tractor would know what tires it could use. The factory owners manual only specs 6-12 farm(ag) fronts for a 4wd. There are no 5-10 farm front tires on 4wd tractors. What is the diameter of a 5-10 ag tire? i can not find how tall it is compared to the 6-12. If it is shorter then can you tell me why they would use it with taller rear tires? The ratio would would be worse with shorter front tires.

You ask some very good questions! And like you said, the kubota web site and info should be correct!

What you really need to do is do the rolling test on your tractor NOW, in 2wd and 4wd and see what is happening, thus finding the magic ratio!

 

[North Idaho Wolfman]

I do notice the difference on the "Tractor Data" website. It is different than the data on the page from my factory Kubota owners manual. What information should i consider correct, the information supplied by my tractor manufacturer or the information supplied by a website? I would think that the factory that made the tractor would know what tires it could use. The factory owners manual only specs 6-12 farm(ag) fronts for a 4wd. There are no 5-10 farm front tires on 4wd tractors. What is the diameter of a 5-10 ag tire? i can not find how tall it is compared to the 6-12. If it is shorter then can you tell me why they would use it with taller rear tires? The ratio would would be worse with shorter front tires.

Yes there is a typo:
For 9.5-16 rears RC 99
you want 5-14 fronts (or any other tire with an RC of 74)

 

[ka24deroadster]

Well, first I am told that if I have 9.5-16 rear tires that I have to run smaller 5-10 fronts. Now I am told that I need to have a larger 5-14 front. Where is this information that everyone keeps giving out coming from? I know that just because something is a "Factory Spec" that does not mean that it is correct. Manufacturers do sometimes send out wrong specs. With that being said, can you tell me why you believe the factory specs are wrong? Kubota only specs a 6-12 ag tire for the front of a 4wd B7200D with 8-16 or 9.5-16 rear tires. Kubota does not recommend a 5-10 or a 5-14 front tire. I have done some math to determine the gear ratios for the front and rear of a B7200D. I use Kubota's online parts lists for all gear specs except for the 12 tooth rear jackshaft gear that I needed to find in my workshop manual. If anyone finds my math or specs to be incorrect please let me know and i will correct it. This is how I calculated the ratios. The rear trans shaft transmits power to the rear jackshaft through a 6 tooth pinion and a 37 tooth ring gear(6.16667 ratio). The rear jackshaft transmits power to the rear axle through a 12 tooth and 55 tooth set of spur gears(4.58333). The overall rear axle ratio is (6.16667 x 4.58333) 28.26388. Now comes the difficult one, the front axle. The rear trans output transmits power to the front trans output through a 16 tooth and 24 tooth set of gears(1.5 ratio). The drive shaft transmits power to the front axle through a 6 tooth pinion and 37 tooth ring gear(6.16667 ratio). The front axle transmits power to the bevel shaft through a 13 tooth and 14 tooth set of bevel gears(1.0769 ratio). The bevel shaft transmits power to the wheel hub through a 16 tooth and 31 tooth set of bevel gears(1.9375 ratio). The total front axle gear ratio is (1.5 x 6.16667 x 1.0769 x 1.9375) 19.3005. Front to rear axle ratio is (28.26388/19.3005) 1.4644. Tire specs very by manufacturer so I am using those supplied by Carlisle because that is what is on my tractor. A 9.5-16 tire is 33.5" tall, a 8-16 is 31.4 tall and the 6-12 is 23" tall. If you divide 33.5 by 1.4644 you get a tire size of 22.876 for the front(error of .54%. If you divide 31.4 by 1.4644 you get a front tire size of 21.442" (error of 7.266%). Given the math, the 9.5-16 tires are what should be on the tractor. The standard 8-16 rear tires give you almost 15 times the ratio error as the "optional" 9.5-16. This information is for the B7200-D. I do not know if it would be different if you have a B7200-hst. It may be the same but I did not verify it.

 

[North Idaho Wolfman]

Every thing you said might be all well and good but to me it doesn't matter!

There is one set of magical #'s to worry about RC (Rolling Circumference),
As long as you keep those #s right, everything will be fine!

6-12 RC 69
8-16 RC 93
=.7419

5-14 RC 74
9.5-16 RC 99
=.7474

They are a close enough match