B7100d get tire sizes

[iangoround]

Hi all.

I'm still plugging away on my repowered b7100. It runs and moves and works pretty good now, but I have a question about tires.

The seller gave me a set of 20x8-10 Carlisle Trac chief r4 tires that are on the front, and the rear is currently Goodyear xtra-tracs in a 31x15.50-15.

I know that's larger than stock, but I'm having a hard time deciphering what SHOULD be on there if I want another r4 tread on the back without putting the ratio too far out of whack so I don't cause problems with the 4wd.



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[Missouribound]

According to tractor data. (tractordata.com) That machine came with either standard or turf tires.

Standard were: Front 6-12: Rear. 8-16
Turf were: Front 20.5 X 8.00-10. Rear 29 X 12.00-15.

Hopefully that will give you an idea. I'm sure your dealer will have a chart somewhere to see what is needed to keep the 4wd in good shape.

And if curious, tractordata.com has a lot of information for that and other Kubota models.

 

[North Idaho Wolfman]

Jump the front tire size up a bit to make up for the larger rears, go to a 22X9.5-10

 

[iangoround]

Jump the front tire size up a bit to make up for the larger rears, go to a 22X9.5-10

Who makes an industrial tire that size? My google-fu is failing me.

 

[North Idaho Wolfman]

Who makes an industrial tire that size? My google-fu is failing me.

Sorry brain fried, I looked up turfs.

 

[iangoround]

I think I figured out how to do math finally.

FRONT: 6-12 RC: 68.9
REAR: 8-12 RC: 92.5
ratio: .7449

current tires:
FRONT: 20x8-10 RC: 57.1
REAR: 31x15.5-15 RC: 93
ratio: .6140 (13% diff!)


proposed change:
FRONT: 23x8.5-12 RC: 68.9
REAR: 31x15.5-15 RC: 93
ratio: .7409 (0.4% diff)

Of course that means I need to find myself some front 12x8 rims with on a 6x4.5 lug pattern. I'm not too sold on this route yet. Steering effort is already a little high, and going to a taller wider tire isn't going to help any. I could go to a 6-12 tire on the front and keep the same F-R ratio, and I bet that would be easier to steer (and find a rim for). However, I don't want to be rutting up the yard too much.

 

[North Idaho Wolfman]

I think I figured out how to do math finally.

FRONT: 6-12 RC: 68.9
REAR: 8-12 RC: 92.5
ratio: .7449

current tires:
FRONT: 20x8-10 RC: 57.1
REAR: 31x15.5-15 RC: 93
ratio: .6140 (13% diff!)


proposed change:
FRONT: 23x8.5-12 RC: 68.9
REAR: 31x15.5-15 RC: 93
ratio: .7409 (0.4% diff)

Of course that means I need to find myself some front 12x8 rims with on a 6x6 lug pattern. I'm not too sold on this route yet. Steering effort is already a little high, and going to a taller wider tire isn't going to help any. I could go to a 6-12 tire on the front and keep the same F-R ratio, and I bet that would be easier to steer (and find a rim for). However, I don't want to be rutting up the yard too much.

I was going to suggest the 23x8.5-12 but I don't know if they will fit and clear things like loader, frame, steering linkage.
And as you too pointed out, bigger tires are hard to steer.

I've got 2 B7100HST's here and I'm working on changing one of them to hydraulic steering, I think it will be a nice add on.

 

[iangoround]

So here's a question. If I wanted to go that route, where can I find a 12x7 6 lug rim that fits?

I'm pretty sure the 23x8.5-12s would fit.

 

[iangoround]

Update: they don't fit.

I remembered that my cub cadet has 23x8.5-12s on the rear. The rims don't bolt up, but even getting it close it's obvious they won't clear the loader frame when turning.

Not sure if 6-12s would be any better.

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[North Idaho Wolfman]

If it's a factory loader then the 6-12's will fit and clear.

 

[Lencho]

Why not change the rears to the original size? 29x12.5-15?

 

[iangoround]

Cost, mostly. My rears are still plenty good and changing rears is much more expensive than changing fronts.

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[zigoapex]

I have b7100d needs new tires on the front, i bought 20.5x8x10 turf (turf on back also) but they look to be bigger than what's on the tractor. am i going to mess up the 4wd? thanks.

 

[Lencho]

I have b7100d needs new tires on the front, i bought 20.5x8x10 turf (turf on back also) but they look to be bigger than what's on the tractor. am i going to mess up the 4wd? thanks.

Hi zigoapex,
what sizes do you have now front and back?

 

[zigoapex]

Hi zigoapex,
what sizes do you have now front and back?

29x1215 on the back and they are 20.5x8x10 on the front. I bought 20.5x8x10 but the rim centers are 4 inch and wont fit. They are going to return them. I’m going to use my old rims so i going to just order the tires.

 

[JosephGozo]

hi

sorry to bump in, given that the B7001 has 5-12 on the front and the B7100 has 6-12 on the front it means that there is a ratio change somewhere. Anyone can tell whether it is in the front axle/ its final drives or the gearbox?

thank you.