TIRES

[maddog2020]

The John Deere 4066r which is the new equivalent to the 4720 is available with the larger 19.5x24. Just thought if I was going to replace the tires I would go with the larger ones. Probably wont gain anything other than to have bigger tires.

 

[RayIN]

Or look up the RC (rolling circumference) of the tire, which is effective circumference taking into account expected tire bulge.

Would that not be entirely dependent on inflation pressure?

 

[hayden]

Would that not be entirely dependent on inflation pressure?

Yes, and I expect it's based on the recommended pressure based on carrying weight. Measuring the diameter with a tape will depend on pressure as well.

 

[sandman2234]

Put a mark on the tire at the bottom of the circle and mark the ground at that point, then drive it forward till the mark is in the same spot and mark the ground again. Measure between those marks on the ground an you will have the rolling circumference.
David from jax

 

[CobyRupert]

Knowing the actual rolling circumference is the best way to know how you will be changing the tire speed (for a given gear, and the ratio with the front tires when in 4wd). If the tires are 3” taller the most the circumference can change is 3(pi) inches, or about 9.42 inches, or less.

…but why are the tires taller? Wear? Aren’t new just wider?

 

[dodge man]

Taller tires are usually considered better are’t they? Better traction? Otherwise big ag tractors would be running smaller tires. I went from a Kubota BX to a JD 2025r instead of a 1025r for the bigger tires. In the OP’s case it might not be worth the effort and expense to go bigger but I understand why he might want to.

 

[jigs_n_fixtures]

On industrial equipment with 4wd, they say not to have the diameter of the tires vary by more than 3%.

Going to a taller tire decreases the power at the tire adhesion point. Because the leverage from the center of the wheel to the adhesion patch is longer.

 

[Jaygyver]

What I did when Firestone stopped making my JD 770 R1 front tire size was to go to their website and miraculously found the rolling diameter in one of their white papers. My front tires were baby butt smooth and the rears were still around 60%.
I found some that were close but were still a couple of inches taller but made sure not to use 4x on the pavement or when not needed, then about 6 months later found some that were almost identical.
I didn't do a lot of bucket work but did definitely fill them to the max or more to save trips across the property.
It's funny, I never had a flat tire on the JD in the 27 years I've owned it even with the smooth tires and I basically used it in the pucker brush as a dozer, burned anything and everything in the fire pit, but within a year of buying the new LS I got a front tire flat. A nail in the tread part of the tire even.

 

[Highlandr]

That larger rear diameter will ruin the front diff. if the fronts are the OEM size. The front tires will always be pushed when in 4WD

Yep.

When I bought the NH TC33 (used) the front turf tires had been replaced with used R4s. Little did I know then that the front tires were smaller diameter than OEM/spec. When driving across the concrete pad in front of the garage the front tires left black marks and they pushed gravel. Until I replaced all the tires I used 4WD only when necessary.