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On MFWD (4wd) tractors it is my understanding a certain ratio must be maintained between the overall diameter of the front and rear tires due to the gear ratios of the front and rear axle.

Per the 4700 manual the R1 tires are 8.00-16 (30.9") on the front and 16.9-24 (52.5") on the rear. Front tires are 58.88% smaller than the rears

Per the 4700 manual the R4 tires are 10-16.5 (30.8" on the front and 17.5L-24 (48.8") on the rear. Front tires are 63.11% smaller than the rears.

A near 5% difference in the ratios seem like a lot. Am I missing something here?

If these numbers are correct, I'll be able to replace the near worn out fronts with the R4s and keep the rears which still have quite a bit of tread on them, no?

Anyone have recommendations on where to get wheels? As much as I like to use OEM wheels, Deere is quite high from what research I have already done.

Thanks for any input
 

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i never did the research ...but it sure looks like you could just change the fronts to r4s as long as you can find the rims ..i will be keeping a eye on this thread ...(i allways just assumed i would have to change all 4 and that seemed to be a non-option)
 

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On MFWD (4wd) tractors it is my understanding a certain ratio must be maintained between the overall diameter of the front and rear tires due to the gear ratios of the front and rear axle.

Per the 4700 manual the R1 tires are 8.00-16 (30.9") on the front and 16.9-24 (52.5") on the rear. Front tires are 58.88% smaller than the rears

Per the 4700 manual the R4 tires are 10-16.5 (30.8" on the front and 17.5L-24 (48.8") on the rear. Front tires are 63.11% smaller than the rears.

A near 5% difference in the ratios seem like a lot. Am I missing something here?

If these numbers are correct, I'll be able to replace the near worn out fronts with the R4s and keep the rears which still have quite a bit of tread on them, no?

Anyone have recommendations on where to get wheels? As much as I like to use OEM wheels, Deere is quite high from what research I have already done.

Thanks for any input
Just looked the JD part number for the front rims for the 10-16.5s would be JD#AM127368 ....im sure there would be a generic for that also
 

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On MFWD (4wd) tractors it is my understanding a certain ratio must be maintained between the overall diameter of the front and rear tires due to the gear ratios of the front and rear axle.

Per the 4700 manual the R1 tires are 8.00-16 (30.9") on the front and 16.9-24 (52.5") on the rear. Front tires are 58.88% smaller than the rears

Per the 4700 manual the R4 tires are 10-16.5 (30.8" on the front and 17.5L-24 (48.8") on the rear. Front tires are 63.11% smaller than the rears.

A near 5% difference in the ratios seem like a lot. Am I missing something here?

If these numbers are correct, I'll be able to replace the near worn out fronts with the R4s and keep the rears which still have quite a bit of tread on them, no?

Anyone have recommendations on where to get wheels? As much as I like to use OEM wheels, Deere is quite high from what research I have already done.

Thanks for any input
You might check with Unverferth

I didn't look at your location but if it's in the east and you can't find a dealer, PM me. I might know one.

Treefarmer
 

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You need to calculate circumference not diameter to compare the sizes.
You need to compare "loaded" radius of the tires.
The front tires should have a 1-5% lead, so the fronts are running slightly faster. I would accept even more lead if you only used MFWD sparingly or only in soft/loose soils.
JD might use different axle ratios, or gearing in the MFWD drive gear box for different tire sizes. A search of JD parts might tell.
For the JD 6XXX series tractors (I have a 6415) there are different front axle, rear axle, and MFWD gear box ratios, since there were many tire combinations. Some of the early owner's manuals even had a section that told how to calculate gear pairs for the MFWD gear box if you wanted to change tire sizes. It may be the case for other JD tractors.
 

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The problem with loaded radius is it varies by tire pressure, load and tire brand/model a lot more then circumference, plus when your buying tires you can’t exactly have them mounted then put them on and measure them to see if it’s what you want for a size.
 

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Discussion Starter #8
Good info guys, thanks

The local contractor tire store has all terrain industrial tires in the stock R1 sizes so they fit the stock trims, reducing my out of pocket costs.
 

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Good info guys, thanks

The local contractor tire store has all terrain industrial tires in the stock R1 sizes so they fit the stock trims, reducing my out of pocket costs.
be sure and post specific good pictures/info of what you end up with sir .....my tire suppliers are a bit short of industrial information
 

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On MFWD (4wd) tractors it is my understanding a certain ratio must be maintained between the overall diameter of the front and rear tires due to the gear ratios of the front and rear axle.

Per the 4700 manual the R1 tires are 8.00-16 (30.9") on the front and 16.9-24 (52.5") on the rear. Front tires are 58.88% smaller than the rears

Per the 4700 manual the R4 tires are 10-16.5 (30.8" on the front and 17.5L-24 (48.8") on the rear. Front tires are 63.11% smaller than the rears.

A near 5% difference in the ratios seem like a lot. Am I missing something here?
I'm in a somewhat similar quandary; I'm looking to replace my R4's with one of the new hybrid R3's, but one available brand doesn't have the correct sizes for the wheels I have, and the other brand, which has tires in my wheel sizes and match the current tire profiles and are advertised, seem to be unavailable unicorns.

I spoke to my local Deere dealer about size disparity and gear ratios; he indicated to me that a 5% difference is acceptable, mainly because there is a clear recommendation in the OM's not to use 4WD on hard surfaces, and on soft surfaces like dirt, snow, sand and mud, there is sufficient slip between the front and rear that there will be no driveline damage or undue wear. I asked if same model tractors delivered with their different option tires (such as turfs vs. R4's on my 2520) had different ratio drives installed to compensate; he said no, the differences in tire diameter were close enough as long as the guidelines about no 4WD on hard surfaces was followed.

Your tire/wheel combinations should be easier than mine to match up with other model Deere or other brand machines to find tire sizes that would suit yours. One other thing to consider if changing wheels is the bolt pattern and wheel offset, especially on front tires to clear the front drive knuckles.
 
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