B2920 different size turfs and gearing???

gabrichter · Feb 11, 2012

I orderd new B2920 requested standard turfs and ended up coming with the bar turfs. Now my question standard turfs/r4'S are 23" front and 33" rear wheras bar turfs are 22" front and 31" back. Does anyone know if Kubota at the factory changes the front/rear gear ratio for the smaller offset size on those barf turfs 22" & 31" vs the turf and R4 size of 23" & 33" or do they figure the extra 1" loss front to back does not affect it. Would seem little extreme to produce tractors with different gear ratio's for that small of a difference and not as common barf turf config setup. I am a little nervous if I decide I do not like the bar turfs and request dealer to change to standard turf tires.

paulemar · Feb 11, 2012

gabrichter said:
I orderd new B2920 requested standard turfs and ended up coming with the bar turfs. Now my question standard turfs/r4'S are 23" front and 33" rear wheras bar turfs are 22" front and 31" back. Does anyone know if Kubota at the factory changes the front/rear gear ratio for the smaller offset size on those barf turfs 22" & 31" vs the turf and R4 size of 23" & 33" or do they figure the extra 1" loss front to back does not affect it. Would seem little extreme to produce tractors with different gear ratio's for that small of a difference and not as common barf turf config setup. I am a little nervous if I decide I do not like the bar turfs and request dealer to change to standard turf tires.

I'm pretty sure that it doesn't matter in a case like this. The TIRES need to be properly matched front and rear so that they will turn in relation to each other. As long as that occurs there won't be any stress on the tranny or gearing when using 4 X 4. Now, if those 2 tire types were mixed with one style/size on the rear and the other style/size on the front that would be trouble, especially on hard surfaces where the is little to no tire slip.

The difference between the 22 vs 23 and 31 vs 33 (1" difference in front, 2" diff. in rear) must be keeping the size ratio in proper balance. That's too much math for me to want to do on a snowy Saturday morning. I'd be betting that Kubota has everything figured out OK.

Tompet · Feb 11, 2012

I wouldn't be too concerned as these seem to be a little known option on Kubota tractors. Kubota would not put them on if they caused a problem. No gearing change.

I had a concern on particular tires I wanted to put on a recent purchase and had my dealer called Kubota in California on the switch, and independently I also called California and spoke with tech and was satisfied with the answers. But this was something different than you are asking as it was off the standard list of tires for the model.

I did drive a friends older Kubota B with these bar turfs which was also used for mowing and I have to say they are a pretty nice tire. More traction and still soft for lawns. There are always a lot of discussions on R4 bar or turf tires on this site and rarely does this option come up. They will have more traction than regular turfs.

To further allay your concerns attached is part of a page from a 2010 Kubota Whole Goods Catalog specifically showing your tires as a standard option. I had a 2920 with R4 bars...you will enjoy the tractor!

CHDinCT · Feb 11, 2012

According to my quick calc's using your nominal tread heights, the ratio of back circumference to front is 1.43 for the turfs and 1.40 for the bar turfs, which I'm pretty sure is within the tolerances of the transmission ratios. Nothing to worry about.