JD 4630 Tire size

bobinIL

Member
The previous owner of my 4630 upgraded my rear tires to 18.4-42 tires I am not sure I like them I am considering going back to 18.4-38 tires. He just used the stepped up rims and a new set of rims is not that expensive and lots of used ones around. Will the smaller diameter tires help with pulling ability? It seems like the tall tires kind of throw the speeds off and do a lot of slipping. They are fully ballasted. It also makes the tractor too tall to go in a 10ft high shed door. My old 4430 with 18.4-38 would just barely go in.
 
Smaller diameter tires of the same width will have a smaller area of ground contact and slower ground speeds. Smaller tires will act like a lower gear ratio: more pull, less speed. If you are fully ballasted and are still slipping with the larger tires, smaller tires will only make the slippage worse (unless your tread is completely worn away). Are the 42's radials or biased ply tires? Is the fuel turned up way over stock on this tractor? That could be causing your slippage.
 
We had purchased a used 4630 in the late 1980's for our farm and it then came with 18.4 x 38 bias ply rear tires, ballasted with 450 pound wheel weights inside each rear inner drive wheel. The tractor was running 170 to 175 horsepower and was equipped with the 8 speed powershift transmission. It was not enough tire and insufficient ballast on the rear for the power that tractor was putting out. I remember plowing in-furrow with this tractor and it slipped quite a bit more with the 38 inch bias ply tires, versus when we switched to the 42 inch radial rear tires. It was only a matter of a year or two before we went with step up rims when we went to the 18.4 x 42 rear tires. We had also put the calcium chloride solution in the inside rear tires, too. This was adequate for holding the power to the ground in high draft conditions, but I would not cite that it was excessive. We opted for the 42 inch rubber for row crop work in 30 inch rows, and this tractor was also our "big horse" at the time, too. We bought another "larger horse" in 1996, and the fluid was pumped out of the rear tires on the 4630 at that time. The 4630 went on "lighter duty" at that time. You are most certainly going to have a larger footprint on the ground with the 42 inch rubber, especially if you are using radial tires on the rear. I am a believer in radial ply tires on tractors greater than 130 horsepower and I have read in ballast recommendations put out by Deere calling for 125 to 145 pounds of total weight per PTO horsepower. Using the 170 horsepower rating and 125 pounds per horsepower rating, you are looking at needing to weight a 4630 at 21,250 pounds with a weight split of 70 percent rear axle and 30 percent front axle, if I recall correctly. I think that is where we had that tractor weighted until the fluid was pumped out of the rear tires. I also do not like the fluid in the rear tires simply because of corrosion when they start leaking, and they ride too harsh and rough with so much less air space in the tires when "juiced" with fluid. The fluid is a less expensive way to add weight versus cast iron, though.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top