3720 small R4 vs large R4

[TC33DA]

My 3720 cab came with the "small" R4 tires. The data I found on the "large"
R4 tires comes up to an inch. Maybe I just don't understand the size numbers. I thought the smaller would keep the CG lower, but an inch is not much (carefull).

 

[dieselram]

I think it's 2 inches total. Standard r4 fronts are 25", bigger are 27". Standard rears are 41" and the big ones are 43". Its a different tread pattern too, kinda curvey on the big ones.

 

[sunnyside360]

I thought the smaller would keep the CG lower, but an inch is not much (carefull).

Not long ago someone here was in process of buying a 3x20 and had some correspondence with Deere -- was told the CG is slightly better with the smaller tires which makes sense. But, is it significant? I personally got the smaller R4's so the tractor/cab would fit into my garage, otherwise I would have gone for the larger tires. Also, I have to say the fixed draw bar is extremely low to the ground with the smaller tires.

 

[WV John Deere]

Not long ago someone here was in process of buying a 3x20 and had some correspondence with Deere -- was told the CG is slightly better with the smaller tires which makes sense. But, is it significant? I personally got the smaller R4's so the tractor/cab would fit into my garage, otherwise I would have gone for the larger tires. Also, I have to say the fixed draw bar is extremely low to the ground with the smaller tires.

Amen to the drawbar being extremely low!!

 

[Reg]

I think it's 2 inches total. Standard r4 fronts are 25", bigger are 27". Standard rears are 41" and the big ones are 43". Its a different tread pattern too, kinda curvey on the big ones.

It is the RADIUS, not the DIAMETER of the tire that affects C of G height and tractor overall height.
So it is a ONE inch difference that makes a difference in tractor height and stability.

The height of the top of the tire is pretty much irrelevant.

 

[greg_g]

My 3720 cab came with the "small" R4 tires.

Mine too, and I found it uncomfortably unstable when carrying something in the bucket. Turns out the standard R1s are only load rated to a total of 6200 pounds. Tractor + cab + HD loader + ballast + operator on mine comes to about 6000 pounds. Didn't take much in the bucket, and the standard R1s were overloaded. **** things were rolling on their sidewalls.

I went to the taller R4s because the 27" front/43" rear very closely matched the R1 rolling diameter. I chose them over the "shorter" R4s (25" front/41" rear) because I'd already experienced the frustratingly low drawbar height. I surely didn't want it any lower to the ground than it already was.

//greg//

 

[hanson1999]

It is the RADIUS, not the DIAMETER of the tire that affects C of G height and tractor overall height.
So it is a ONE inch difference that makes a difference in tractor height and stability.

The height of the top of the tire is pretty much irrelevant.

huh???

if the top of the tire is 2 inches higher the tractor will sit 1 inch higher...thats pretty simple to figure out....

take total height difference and split it in half to figure out height change....

most tires give the diameter not the radius so thats the easiest way to figure out heights....

 

[Reg]

huh???

if the top of the tire is 2 inches higher the tractor will sit 1 inch higher...thats pretty simple to figure out....

take total height difference and split it in half to figure out height change....

most tires give the diameter not the radius so thats the easiest way to figure out heights....

Yes,
That IS what I said (-:
It was in contradiction to the post suggesting that the height difference would be TWO inches.

 

[Zebrafive]

Mine too, and I found it uncomfortably unstable when carrying something in the bucket. Turns out the standard R1s are only load rated to a total of 6200 pounds. Tractor + cab + HD loader + ballast + operator on mine comes to about 6000 pounds. Didn't take much in the bucket, and the standard R1s were overloaded. **** things were rolling on their sidewalls.

I went to the taller R4s because the 27" front/43" rear very closely matched the R1 rolling diameter. I chose them over the "shorter" R4s (25" front/41" rear) because I'd already experienced the frustratingly low drawbar height. I surely didn't want it any lower to the ground than it already was.

//greg//

I am surprised JD would offer tires that they know would be overloaded so easily. How much capacity did the R4s add? Hopefully more than the loader capacity. Did you complain to the dealer or JD?

 

[Reg]

I am surprised JD would offer tires that they know would be overloaded so easily. How much capacity did the R4s add? Hopefully more than the loader capacity. Did you complain to the dealer or JD?

R1s are primarily for FIELD work, known colloquially (to some) as "tractoring" (-:
Front R1 tires are usually very low rated, which for FIELD work is generally OK.

R4s are for LOADER work, they are rated much higher - - do the arithmetic, simply hanging the loaded bucket 4 or 5 ft out there represents a lot more than the mere weight of the bucket and its load.
Cantilevered.

Consider that a lot of first time buyers pick up their "tractor smarts" from forums such as this.
MANY MANY tire threads proclaim R1s as being the traction meisters - and under certain conditions they ARE.
Very few threads discuss the need for R4s for loader work and/or the inadequacy of R1s on the front for loader work.

It really comes down to knowing what you will use the tractor for before you buy it - or being prepared for surprises if you use it differently to its configuration (-: