TIRES

[maddog2020]

I have a 2009 JD 4720. The rear tires are shot. They are R4 s. I replaced the front tires last year wit factory size 10x16.5. The rears are 17.5x24. I would like to replace them with 19.5x24s. I know they will fit they are only about 3 inches taller. My question is will this be a problem when tractor is in 4wd. I noticed same size tires tire vary a couple inches any from manufacture to manufacture

 

[dodge man]

I’d say three inches taller is to much.

 

[RayIN]

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

 

[maddog2020]

So id i decided to go with the larger rear dire what size would i need to put on front. Is there a chart a formula to figure that out?

 

[dieselscout80]

You want the fronts to turn slightly faster than the rear tires (called lead IIRC) and going larger on the rear will reverse that and not work.

That said look at the correct front to match the 19.5 tires. On the NH TC series the ones with 19.5 rear use a larger 12.5x16.5 front tire.

Maybe JD has an another tractor with them.

 

[scootr]

Curious why you want to change the tire size ...

 

[RayIN]

So id i decided to go with the larger rear dire what size would i need to put on front. Is there a chart a formula to figure that out?

Measure the OD of both front and rear tires(new) that came OEM, measure exactly,with tires off the ground; the more precise the better the outcome.
Then apply that differential ratio to prospective new tires.

 

[hayden]

Measure the OD of both front and rear tires(new) that came OEM, measure exactly,with tires off the ground; the more precise the better the outcome.
Then apply that differential ratio to prospective new tires.

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

 

[skipmarcy]

My Mahindra came with 10-16.5 on front and 17.4-24 on the rear (R4s) and I was snapping front axles quite a bit with the heavy loader work I did. After going back & forth with them and busting a front diff. I had to repair out of warranty, they told me the tractor should have had 16.9-24 on the rears from the factory. I had to purchase the tires myself and sold the originals to a guy with a backhoe. The axle breaking dropped to virtually none after the tire change. In later years I also went to 12-16.5 for my fronts and has been doing well for quite a few years. Lack about 3 hrs. of hitting 3300 hrs. on the clock.

 

[John0829]

If you put larger tires on the rear then you are changing the ratio between the front and rear... something is going to break and that something will be expense parts. If and I do mean IF you really want larger tires on the back then change to fronts to larger ones as well.

But what is it you expect to gain from the larger tires?