John Deere 770 tires??

deeregirl85 · Nov 1, 2011

Hello everyone! I am having quite a problem with a company tractor and I am hoping someone can help!

I work for college that has a JD 770 CUT 4WD that is used for landscaping purposes and just recently had some parts in the front end go Bang! Well now that the tractor is all back together I am having some serious doubts that the tires on the front of it are not the correct size...

The tires are 155/80R12 passenger car tires and I don't think these are the right size?! I have gone to the dealer and was informed that the original tires are obsolete so no help there..

Can someone please tell me the correct size that goes on the front of this tractor? I do not want to put on the traditional tires as I know it will tear up our grounds so I am hoping to find a lighter duty/turf tire, I guess, to put on the front.

Thanks in advance!

arrow · Nov 1, 2011

Turf tires for this tractor measure 13.6x16 rears and 23x8.50-14 fronts

deeregirl85 · Nov 1, 2011

arrow said:
Turf tires for this tractor measure 13.6x16 rears and 23x8.50-14 fronts

Thank you very much for responding to my post

But the size you listed above 23x8.50-14 will not fit the rims on our tractor..? As per the dealer this tractor came with either 5.00x12 or 6.00x12 tires but that was all the info I could find..?

irwin · Nov 1, 2011

deeregirl85 said:
Thank you very much for responding to my post

But the size you listed above 23x8.50-14 will not fit the rims on our tractor..? As per the dealer this tractor came with either 5.00x12 or 6.00x12 tires but that was all the info I could find..?

Not sure where that dealer is getting his info. The 770, 790 and the 3005 all have the same front wheel lead ratio: 1.571 .. you might have to buy new rims for the front if you go with turf tires... rear= 13.6-16, frt= 25x8.50-14.. if the 3005 has different sizes listed you should be able to use them..

You MUST have the proper front wheel lead or serious damage to the front axle or the drive for the front can occur.

You haven't told us what type of tire is on the rear. R1? R3 (turf)? or R4? If you have R1 (ag) tires you will need to be very careful putting anything other than the corresponding front tires on. Take a look at the rear tires and post here what size and style they are.

I did a lot of research on my old 770 when I changed tire type from R3 to R4. Here's a couple links to older threads that have info that might be useful.

http://www.tractorbynet.com/forums/parts-repairs/96441-turf-tires-should-go-industrial.html

http://www.tractorbynet.com/forums/john-deere-owning-operating/99396-790-770-mfwd-ratio-r4.html

deeregirl85 · Nov 1, 2011

irwin said:
Not sure where that dealer is getting his info. The 770, 790 and the 3005 all have the same front wheel lead ratio: 1.571 .. you might have to buy new rims for the front if you go with turf tires... rear= 13.6-16, frt= 25x8.50-14.. if the 3005 has different sizes listed you should be able to use them..

You MUST have the proper front wheel lead or serious damage to the front axle or the drive for the front can occur.

You haven't told us what type of tire is on the rear. R1? R3 (turf)? or R4? If you have R1 (ag) tires you will need to be very careful putting anything other than the corresponding front tires on. Take a look at the rear tires and post here what size and style they are.

I did a lot of research on my old 770 when I changed tire type from R3 to R4. Here's a couple links to older threads that have info that might be useful.

http://www.tractorbynet.com/forums/parts-repairs/96441-turf-tires-should-go-industrial.html

http://www.tractorbynet.com/forums/john-deere-owning-operating/99396-790-770-mfwd-ratio-r4.html

Sorry I am still new in the JD world lol! Our tractor has R1's on the rear (12.4-16) I will post a picture of it when I get home tonight.

I have read a few posts on here regarding tires and I already understand the improtance of having the "right size" tires for any application. Especially 4WD's. (just like my pickup that had 4.10's in the rear and 3.73's in the front when I bought it and didn't know...)

So this is why I ask if the tires that are on it are any where close to the size they need to be or not? I have a very tight budget to stick to on getting tires for this tractor since we just put over a grand in repairing the front end.

If it ends up me having to find 4 tires for it then so be it but I am/was really hoping that I don't have to go that route...

scrappy isb67 · Nov 1, 2011

arrow said:
Turf tires for this tractor measure 13.6x16 rears and 23x8.50-14 fronts

this is also the size for the R4's I believe

deeregirl85 said:
Thank you very much for responding to my post

But the size you listed above 23x8.50-14 will not fit the rims on our tractor..? As per the dealer this tractor came with either 5.00x12 or 6.00x12 tires but that was all the info I could find..?

The 5.00x12 and 6.00x12 are R1 sizes

The tires on the frontend now are too short I would bet. but if you aren't in 4wd ALL the time , it shouldn't cause an issue

grsthegreat · Nov 1, 2011

this is what tractor data shows

TractorData.com John Deere 770 tractor dimensions information

4.0-15 front and 9.5-24 rear

My old 870 had the same "go bang" front end and i think the bill was about $1,300 to repair as far as i remember.

deeregirl85 · Nov 1, 2011

scrappy isb67 said:
The 5.00x12 and 6.00x12 are R1 sizes

The tires on the frontend now are too short I would bet. but if you aren't in 4wd ALL the time , it shouldn't cause an issue

I honestly do not know how often it is in 4WD or not...I'm just the mechanic so I don't ever see our equipment till something goes wrong haha. Which hopefully will not be for quite a while with the JD...But regardless if these tires will work for now or not they are almost shot and I Do Not want to put passenger car tires on it again...especially if they are too small. I can get the R1 tires easy but unfortunately they can't go on it because they are afraid of messing up the campus with them :-/

deeregirl85 · Nov 2, 2011

Here is a picture of our Deere

sriddle1ny · Nov 2, 2011

Deeregirl85,
I recently purchased a "04 JD790 and have been doing research on its operation. The old saying "Don't know what I don't know" applies with me so proper ballest and weight distribution came to mind whenlooking at the 770 picture you posted with the Loader, I don't any wheel weights nor a ballast box if you're doing any heavy lifting. I noticed grsthegreat mentioned the "go bang" front end, you might want to read this thread, again not sure if it applies to the 770 or the tractor pictured is 4WD..........

http://www.tractorbynet.com/forums/john-deere-owning-operating/171692-jd-790-front-end-problems.html