Farm Equipment - 8070 tire replacement to 20.8x42?

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8070 tire replacement to 20.8x42?

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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=174275
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Topic: 8070 tire replacement to 20.8x42?

Posted By: Ron(AB)
Subject: 8070 tire replacement to 20.8x42?
Date Posted: 10 Sep 2020 at 10:47am

My fwd 8070 has 20.8x38 and they are due for replacement. (sidewalls are cracking - Armstrong radials - lost the fluid in one this spring and it has two boots already)

The front has 18.4x26 and the tractor is always pointing uphill. And they have worn more than the rears.

Putting on taller rears should level it out.

Will it work? Has anyone else done it? Was it a success?

Replies:

Posted By: Acdiesel
Date Posted: 10 Sep 2020 at 11:03am

you don't want to change the tire size ratio or you will cause a binding on your drive train.

The last number is your rim size, are you replacing your rims?

front to rear need to match Ratio size. I would go with what your operators book says.

you can look on tractordata.com for tires sizes as well if you don't have a book.

looks like you should have 14.9-24 or 14.9-28 on the front.

Dan

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D19 Diesel,D17 Diesel SER.3
2-D14, 2-D15 SER.II WF/NF
D15 SER.2 DIESEL
D12 SER.I, D10 Ser.II
2-720'S D21 Ser. II

Gmc,caterpillar
I'm a pharmacist (farm assist) with a PHD (post hole digger)

Posted By: victoryallis
Date Posted: 10 Sep 2020 at 11:09am

I hate how my 8050 is always nose up with the 18.4 26 tires. I bought the rims to go to the skinny 28 inch rubber. Plan is next spring she’ll sit even like the 30 does.

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8030 and 8050MFWD, 7580, 3 6080's, 160, 7060, 175, heirloom D17, Deere 8760

Posted By: DrAllis
Date Posted: 10 Sep 2020 at 12:06pm

18.4 x 26 was an option in 1984 ?? with the 20.8 x 38 rears. Pretty sure it was borderline being too big even for the 20.8 x 38 rears. Front axle speed is always to be a little faster than the rear, like maybe up to 5% or so.

Posted By: fourthgeneration
Date Posted: 11 Sep 2020 at 11:17pm

That was the largest tire for loaded radius listed.it is an inch larger radius then the next two listed for the front.

Posted By: ajl
Date Posted: 12 Sep 2020 at 11:18pm

Buddy of mine has 20.8 x 42 on an 8070. It has step up rims on it. Not sure what the front tire size is. I have driven that tractor and seems to work well with it. My 8070 has 20.8 x 38 with i think 16.9 x 26 on front which seems to be a good combo. It sits level. Too dark to check it now.

Posted By: Ron(AB)
Date Posted: 14 Sep 2020 at 10:19am

I was concerned about the clearance under the cab fenders.

It probably would give an increase in road speed? maybe 1 mph?

I think I'm going to do it.

Posted By: Joe(TX)
Date Posted: 20 Sep 2020 at 10:10am

If you change the rear size, you have to change the front to keep the ratios matched since it is a FWA.

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1970 190XT, 1973 200, 1962 D-19 Diesel, 1979 7010, 1957 WD45, 1950 WD, 1961 D17, Speed Patrol, D14, All crop 66 big bin, 180 diesel, 1970 170 diesel, FP80 forklift. Gleaner A