I just bought a Used 2016 John Deere 310SL backhoe. I noticed the rear tires are 21-24. Every other John Deere I have owned had 19.5-24. The 21 are bout 2.5” bigger diameter. When these wear out I would like to put 19.5s Do you think the gearing is different between the two? Or is the difference in diameter not enough to matter?
2 or 4 wheel drive? I think that's to much difference for a 4 wheel drive machine. Should measure the circumference between the two. could be quite a bit. If its 2 wheel drive than I don't think it will matter.
4x4
Yeah 4x4 will take out diffs and u joints quickly
According to the 310SL operator manual I found, 19.5L-24 was only available for 2wd. The difference in rolling circumference ratios is 2.5% which is pretty steep. I don't know a lot about backhoes, but if 4WD ones work like to MFWD tractors that could double the front axle overdrive.
The chart you found is the different tires available for the front and rear axle independently. My other backhoes are 4x4 all with 12.5-80-18 on the front and 19.5-24 on the rear.
Transfer case ratio could be different if you give me serial number i can call my dad...he has the parts manual....it would tell us if different ratios were available
What makes you say the chart is for the axles independently? if they were independent, then I would expect a much longer chart showing the allowable combinations for 4wd.
The chart is for recommended air pressure for all the different size tires available. It’s in the Maintance section of the owners manual.
First thought that comes to mind is that you don't always run in four wheel drive so what difference would it make between the 19.5 and the 21 tire. Second item is that the front axle steering which will always put strain on the front drive line when locked in four wheel. There will be wind up! Last item is what is the difference in height between a 19.5 and a 21 inch tire fully inflated? The only problem I really see is whether or not the wheel widths would enable the bead on the 19.5 to seat easy.
On the John Deere parts advisor it appears to me that 2wd and 4wd use the same front wheels n tires. I replaced my own rear 19.5's with 21l's a few weeks ago and am glad i did. The major difference was the total width in them.There was only a couple of inches in height difference, but it the tire was a lot closer to the frame of the tractor.
My 420D has 19L-24's on the rear. Getting 2 new Galaxy's on it tomorrow.
In regards to the rear differential gearing for different size tires. I took another look in the John Deere Parts Advisor today. There is only one pinion gear available for the 310SL. I may be wrong ,but that is an indication the bigger tires are not a factor in any harmful added strain on the front differential. Someone correct me if I am wrong.