Need help / input on tire size

[jwild]

Long time reader, first time poster.

At the begining of the year I was approached by the city to mow city roadsides. Long story short I came across a used Kubota M8200 Cab MFWD Loader and bought a new 8' rotary cutter.

After using the tractor this season I felt like it was a little under powered and a few times operating temps got a little warm. To the average guy this tractor would be fine, but I prefer to have more tractor than not enough so it's not having to work as hard.

Came across an awesome deal on a Kubota M125x. The only downside is the M125 is huge when compared to our M8200. The M125 has 18.4R38's on the rear and 14.9R24's on the front. Part of why I thinks it sits so high?? Physically the M8200 is the perfect size but doesn't have the power to get the job done. This year we will be picking up additional roadsides and will be pulling around a 15' cutter when we need to. (hints the larger tractor size needed) Is it possible to put 18.4R30's on the rear of the M125 to help reduce some of the height? Has anyone done this before or heard of this being done? I did measure the bolt pattern and everything would match up. Any help or suggestions would greatly be appreciated.

I'm open to any tractor brand or model. It just so happens that a Kubota dealer is right next door to our shop and there is a John Deere dealer on the north side of town. Thanks!

 

[murphy1244]

:welcome:

 

[MIKE R]

Welcome to the forum. If it is 4wd is can not be done as it will tear out the drive if engauged. Remember that it will also slow down your speed in each gear. You will also have to change the fronts or it will ride nose up and look goofy.

 

[LD1]

Anything is possible. But it certainly isnt going to be cheap.

IF you like math, it isnt hard to figure out. But part of it is looking up specs on different tire sizes. This is where a good local tire-shop that deals with farm tires can help by whipping out a big ole book of tires.

But basically, as Mike R said, you will tear up your 4wd if you do just the backs.

You need to look up the tires you have now, fronts and rears, and see what they list as their rolling radius or circumfrence. Then you can see what the ratio is for front to rear.

Just an example: if the rolling radius if the fronts is 25" and the RR of the rears is 32", your fronts are 78.1% of the size of the rear. If you want to go to a 28" front....28 x 0.781=21.8. So you would need a tire with a RR of 21.8" for the front.

 

[jwild]

Very good point Mike and LD1, thank you. So if the fronts come 63.16% smaller than the rears to swap out to a 18.4R30 I would ideally need to run a 18.9" tire up front. Only problem is there isn't a 19" tire manufactored, only a 18's or 20's. Doesn't sound as if it would be a good idea as the last thing I need to do is replace the 4wd.

Any ideas for a tractor size that might be a better fit? Forgot to mention I ideally want to push a 10-12' snow box in the winter, not a deal breaker if the tractor's not big enough, just trying to get the most use out of my investment.

 

[MIKE R]

Have you looked at the Massey Ferguson Low Profile tractors.

 

[Gary Fowler]

It is hard to imagine needing a 125 HP tractor to mow with a 15 foot mower. I would think your 85HP would be plenty.
Now as for tires and low profile, I think every manufacturer must have a low profile tractor for mowing on the highways as everywhere I go I see different brands being used and they all seem to have low and wide tires. Check with your dealer and see what they recommend. Likely to be a special order but I am positive that they all have models to do what you are asking.

 

[LD1]

Might want to double check the numbers. I am showing the 18.4-38 with a rolling circumfrence of 206 and the 14.9r24 with a rc of 148.

148/206=71.8%

the 18.4r30 is 178

178*.718 is 127.8

I'm seeing that an 11.2x24 is pretty dang close

What numbers did you use?? if you were using rolling radius, are you sure that you didnt mean you need a tire with a radius of 18.9"??

here, this is pretty good for giving lots of tire information Firestone Agricultural Tire