JD770 4WD - Front wheel replacement

NHR24 · Jul 1, 2020

Greetings all, I'm new to the forum and new to tractors in general.

I have a new-to-me JD 770 4WD that needs a new front wheel. I was out mowing our hunting property a few weeks ago and a stump found it's way under the front wheel. It managed to bend the lip of the rim over and destroy it. I don't think it's repairable.

The JD # is AM876649. The wheel is marked 12x4JA and the tire is a 6-12 R1.

I'm having a heck of a time finding a replacement. It appears JD no longer supports this model and I can't find any new-old stock. From what I can gather the 4-12 rim is an oddball size since I can't seem to find any aftermarket wheels in that size.

Do you guys have any suggestions? Miller Tire has a wheel listed as 4x12, but they also list the tire size as 4x12.

kthompson · Jul 2, 2020

Sadly it is easy to damage a tractor in the woods. I may be not understanding but are you saying the tire is a 6 x 12 but the rim is a 4 x 12? Your last sentence uses 4 x 12 as rim and tire size.
Does seem you could find a salvage yard if nothing else.

3Lfarms · Jul 2, 2020

You’d be surprised what they can do to repair wheels. If it’s just bent, I bet you can find someone to straighten it. It’s only steel. Correct application of heat and it becomes easy to work with.

NHR24 · Jul 2, 2020

kthompson said:
Sadly it is easy to damage a tractor in the woods. I may be not understanding but are you saying the tire is a 6 x 12 but the rim is a 4 x 12? Your last sentence uses 4 x 12 as rim and tire size.
Does seem you could find a salvage yard if nothing else.

The wheel is stamped 12x4JA, but it currently has a tire marked 6-12 R1. Tractor Data also says the 4WD tire size is 6-12.

The wheel listed on Miller Tire says that the wheel size is 4-12, but it also says the correct tire size is 4-12. I'm a bit confused by the tire size nomenclature for tractors, its completely different from road tires.

From what I understand I can't just get a different wheel & tire because I need to maintain the front/rear drive ratio, correct?

Here is the damaged wheel:

Peter 315 · Jul 2, 2020

I got new rear rims for my JD770 a few years ago , Rims for a JD790 should fit that's what a bought......

NHR24 · Jul 2, 2020

Peter 315 said:
I got new rear rims for my JD770 a few years ago , Rims for a JD790 should fit that's what a bought......

That's good to know! Thank you! I'll see if I can also locate a salvage 4WD 790.

Peter 315 · Jul 2, 2020

JD 790 ......Ag front: 6.00-12 (early)
5.00-15 (2WD)
7.00-14 (4WD)
Ag rear: 12.4-16 (early)
11.2-24
Lawn/turf front: 25x8.50-14
Lawn/turf rear: 13.6-16
Industrial front: 25x8.50-14
Industrial rear: 15.0-19.6