Mixing R1s and R4s

EMF

New member

Equipment
Kubota L5040
Feb 25, 2021
2
0
1
Monmouth, Oregon
Greetings, new guy with a new to me Kubota. Just acquired an L5040 in good shape outfitted with stock size R1 ag tires front and rear, lots of tread. I really like this tractor but one thing I don't like is the relatively high stance. We mow pastures twice a year, there are numerous sidehills. I've been using a JD 3033 for some time - good little machine, no complaints, but its just not big enough and takes forever to mow our acreage with a 5' deck. Never flipped it but the pucker factor is high on the sidehills. The 3033 has a low center of mass, that helped quite a bit.

Talked to the sales guy about what I can do to widen the stance of the L5040. For the record he was candid about what Kubota will and won't do. In his words, 'We have limited options, we're not a tire company. We can sell you new R1, R3, and R4 tires mounted on new rims and that's it.' He strongly recommended the local Les Schwab farm store for expanded options, I appreciated his honesty. He showed me the adjustment on the rear wheels to move them out 2' on each side so I'm doing that. But that doesn't help the fronts, they are 9.5-16s, they feel narrow and close in. These are the ones I'm really concerned about. Looking around the lot I saw a brand new MX tractor with some beefy R4s, the fronts were 12-16.5s on what are clearly wider rims. I measured the horizontal OD of the 9.5-16s on the L5040, came in at 32". Then measured the OD of the 12-16.5s on the MX and found them to be 32" also. The bolt patterns also match, 6x6".

Has anyone swapped out their front R1 ag tires for wider R4s to improve stability on a utility tractor like this? While keeping the stock R1s on the rear? I believe I've seen some Kubotas where this was done but let me ask this forum if there are known issues with doing it? The only one I can imagine is possible interference with the axle going from lock to lock if the offset isn't enough (I wasn't smart enough to measure that). Regarding the drivetrain the tractor should not know the difference if the diameters match.

Let me know what you know please and thanks, looking forward to the responses.
 

85Hokie

Well-known member
Lifetime Member

Equipment
BX-25D w/ Filled Rears,2" Spacers,PTB. Under Armor, 90'-90'-92'-B7100HST's
Jul 13, 2013
8,015
397
83
Bedford - VA
The first thought is that it will mess up and bind your 4wd system - however, since you have done the math and measured the diameter of the front end and found them to be the same - if the bolt pattern works also then it may very well work fine.

Now the question that still comes up - since these tires/rim are on 2 difference machines - will the steering work perfectly as designed? Will the lock to lock hit anything? As you mentioned - the hub offset will come into play.

Do you spend a lot of time in 4wd?

If you have a relationship with your dealer - you may be able to "place" them on and try it - but I am going out on a limb here and say, they want to be paid for first.



Here is your factory choices as you may be aware:

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BigG

Well-known member

Equipment
l2501, FEL, BB, Rotary cutter, rake,spreader, roller, etc. New Holland TL80 A
Sep 14, 2018
1,425
307
83
West Central,FL
Greetings, new guy with a new to me Kubota. Just acquired an L5040 in good shape outfitted with stock size R1 ag tires front and rear, lots of tread. I really like this tractor but one thing I don't like is the relatively high stance. We mow pastures twice a year, there are numerous sidehills. I've been using a JD 3033 for some time - good little machine, no complaints, but its just not big enough and takes forever to mow our acreage with a 5' deck. Never flipped it but the pucker factor is high on the sidehills. The 3033 has a low center of mass, that helped quite a bit.

Talked to the sales guy about what I can do to widen the stance of the L5040. For the record he was candid about what Kubota will and won't do. In his words, 'We have limited options, we're not a tire company. We can sell you new R1, R3, and R4 tires mounted on new rims and that's it.' He strongly recommended the local Les Schwab farm store for expanded options, I appreciated his honesty. He showed me the adjustment on the rear wheels to move them out 2' on each side so I'm doing that. But that doesn't help the fronts, they are 9.5-16s, they feel narrow and close in. These are the ones I'm really concerned about. Looking around the lot I saw a brand new MX tractor with some beefy R4s, the fronts were 12-16.5s on what are clearly wider rims. I measured the horizontal OD of the 9.5-16s on the L5040, came in at 32". Then measured the OD of the 12-16.5s on the MX and found them to be 32" also. The bolt patterns also match, 6x6".

Has anyone swapped out their front R1 ag tires for wider R4s to improve stability on a utility tractor like this? While keeping the stock R1s on the rear? I believe I've seen some Kubotas where this was done but let me ask this forum if there are known issues with doing it? The only one I can imagine is possible interference with the axle going from lock to lock if the offset isn't enough (I wasn't smart enough to measure that). Regarding the drivetrain the tractor should not know the difference if the diameters match.

Let me know what you know please and thanks, looking forward to the responses.
The width of the front tires will have very little affect on the stability of your tractor. The front axle is set on a pivot. The rear wheel width is going to be used to add stability. Add wheel weights to improve the stability. Along with setting the wheels to the widest width.

If you think you still want to make the front end wider you could add wheel spacers to the front axle. This will not change the ratios of the 4 x 4 and most likely cost less.

Also think about adjusting the pattern you use to mow the pastures so that you are traveling up and down the hills as apposed to traveling across the hills.
 
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jimh406

Active member
Lifetime Member

Equipment
Kubota L2501 with R4 tires
Jan 29, 2021
163
88
28
Western MT
You should see if your rims are mounted as far out as possible, load them, and see if you can add weights to your rims. You could also potentially add spacers. I’d check into those first as well as make sure that your tire pressure is near the higher recommended range to prevent the tires from flexing as much.
 

D2Cat

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Lifetime Member

Equipment
L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
9,594
691
113
40 miles south of Kansas City
What BigG said is right on track. Adding the weight in the rear tires will have the greatest effect, and the least cost. Each of your R-1 tires could use 48 gallons and (depending what the product was) weigh 400#.

 

EMF

New member

Equipment
Kubota L5040
Feb 25, 2021
2
0
1
Monmouth, Oregon
Thanks for the input, was hoping someone had tried this, maybe I'll break new ground. Responses:

- We're in 4 wheel drive about 25% of the time.
- Didn't know there are spacers available, I'll look into that.
- The problem with mowing hills the other way is you have to turn back down the slope at the top (there's a fence), that's where I've come closest to tipping. Sideways has proven the lesser evil.
- We are moving the rear wheels out 2 inches each side, the max they can go. That will put the tire sidewalls in line with the sides of the loader bucket at 72".
- The rear tires are filled with beet juice ballast.

Dropped by the dealer today, they will sell me what I want as long as I put it on. Fair enough. In between rain squalls we pulled a new MX with the 12-16.5 fronts up next to my tractor for comparison. The ground wasn't as level as I would have liked but it was close enough. I rechecked the diameters, they are within .25". The extra width appears to be evenly distributed on both sides of the hub centerline. I'll check axle clearance with steering lock and if that works will do the swap. BTW the rims for the 12-16.5 tires are 16.5-9.75. I'm not getting rid of my ag tires, there will be times we'll want to use them.
 

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sheepfarmer

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Lifetime Member

Equipment
L3560, B2650, Gator, Ingersoll mower
Nov 14, 2014
3,858
216
63
MidMichigan
I am not sure changing the front tires will do that much for stability. I will be the third person to vote for adjusting your mowing pattern for safety, even if not most efficient. If the lower part of the hill can be done going crosswise, do it first, and then BACk up the hill, slightly change angle then go forward down, doing that upper steeper section as a series of zig zags.

My mower cuts as well going backwards as forwards, but even so I have a section of a bank that I drive around in a large circuit so that I only mow it pointed straight down hill, and it takes several loops. If you have a fence there you can't do that.
 

85Hokie

Well-known member
Lifetime Member

Equipment
BX-25D w/ Filled Rears,2" Spacers,PTB. Under Armor, 90'-90'-92'-B7100HST's
Jul 13, 2013
8,015
397
83
Bedford - VA
I have a section of a bank that I drive around in a large circuit so that I only mow it pointed straight down hill, and it takes several loops.
I had to do the exact same thing when I had my old 53 Ford - it was a very long way around too!
And with a 2 wd drive tractor - that was fun if even a tad bit wet!!!:unsure:
 

Brian H

New member

Equipment
MX5200HST, MTL RK5 Gr, Ford 850, King Kutter brush hog, rototiller, blade, disk.
Feb 8, 2019
27
8
3
Waupaca, WI
Too bad you are so far away. Ive got a set of 12.5-16 R4s off my MX5200 that i would sell you. They are on the rims and have 200 hrs on them. I hated R4s and switched to R1s.
 

DustyRusty

Active member

Equipment
BX22, BX2750 Blower, BX2763 Blade, BX Power Broom, BX23S w/ Cab
Nov 8, 2015
543
96
28
North East CT
Put a tilt meter on your tractor, and see actually the amount of slope you are dealing with. I lost a friend that used the same JD to cut the field, and one day, the tractor turned over and killed him. He had been cutting that field for over 15 years with the same tractor, but something changed that day, and no one knows what it was. I flipped a tractor once, and now, I only go up and down the hills, never across.
 

D2Cat

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Equipment
L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
9,594
691
113
40 miles south of Kansas City
The stability of the tractor is determined by the dynamics of the rear of the tractor, weight, wheel width, traction, etc. The front tires will remain "unstable" because the front axle pivots up and down at the center point.