New Tires Kubota B7100 Turf Tire replacements

[ant126]

I have gotten some great information on this already from browsing through previous threads on this forum, but I just wanted to run this by any of you who have been in a similar spot and had either good or bad luck with your tire replacements.

I have got to replace some worn out front tires on an 81-82 Kubota B7100 HST 4wd. They are old style 4 lug wheels. My rear wheels were there when I bought the tractor and they are oversized Goodyear Terra Z Bar tires 31 * 15.50 - 15. Their RC (per the manufacturer) is 89. The front wheels I am replacing are worn almost bald 20.5*8.0-10 (not sure of their RC). I can either go with tires that have an RC close to the original (61) or should I try to find something slightly larger?

Using a formula I found on another thread here, if the B7100 has a gear ratio of 1.466, and if the Kenda K378 tires (I have seen mentioned also on this forum) have an RC of 62 and my rears have an RC of 89.

1.466 x 62 = 90.89 then / 89 = 1.021 Then (1.021 - 1 )x100 = 2.1% Which is within the 1-5% sweet spot and when I take 62/89 I get .699 (but I don't have the factory rear tire RC to use to compare this to.) As a side note I also have no binding issues right now with my current tires, but I also have no traction with them.

 

[SRG]

http://www.orangetractortalks.com/forums/showthread.php?t=34450

Here is my thread with info from when i just changed my tires from turf to R4. There's a calculator in the 2nd to last post that will help. Hopefully it helps you some.
I can't advise on your specific tire size choices, as i don't know what your originals were or how you want to upgrade.

 

[torch]

What kind of tire are you after? Your subject title seems to suggest you are after turfs, but the K378 is an ag style tread -- similar to your Goodyear rears, IMHO. And your math shows the rolling circumference is a reasonably close match, so they would be fine, especially if you are playing in the mud or snow where things will be slipping anyway. You can always shift to 2wd when driving on a hard surface if you are worried about binding.

However, if you are after a turf style, then the only two choices are a Kenda trailer tire or a Carlisle ATV tire ("All Terrain 2"). I measured the rolling circumference of my 20 x 10 x 10 Carlisles to be 60.25" @ 22PSI holding up a FEL. Plug that into your formula and we get:

1.466 x 60.25 = 88.3265 then / 89 = .992 Then (.992 - 1 )x100 = 0.8%

So the AT2 would be fine for you too.

Are you going to be playing in the mud, or driving over your lawn?

Edit: here's the AT2 beside a trailer tire. a bit more aggressive than a turf tire, but no where near as aggressive as that K378:

 

[ant126]

SRG Thanks for the link.

Torch: I was looking for something atleast somewhat more aggressive than regular turfs. Either the K378 or the Carlisle All Terrain II would be fine for me - tread wise. I was really only leaning toward the K378 because of the possible 2 more inches in RC (I emailed the manufacturer of the K378 and I'm still waiting to hear if the RC is 62). I will probably never have the tractor on hard surfaces like concrete, pavement, or rock. BUT I am on slopes brush hogging often, and I use a small plow from time to time and I use 4wd most of the time while I am doing both of these so getting as close to the original ratio as I could between the tires is what I was shooting for.

 

[torch]

Bear in mind that the RC is a variable that changes with load and tire pressure. It'll be smaller driving along with a full FEL bucket and larger driving back for the next load. As long as the ground surface has a bit of give, you should be fine with either one. I suspect the Kenda has the edge on traction in loose stuff.

 

[Lencho]

Hi Ant. I can vouch for the K378 as great front tires if you want traction. My rear tires are the stock 29.5 diameter, not over sized. The tire is about the same size as the trailer tire it replaced.
I find the combo much better for subsoiling, box blade and loader work. No problem shifting in or out of 4 wheel drive or binding.

 

[ant126]

Torch: Thanks for all the great information!

Lencho: Great. Yeah the Kenda tires sure look pretty serious.