Different size tire that OEM on 4wd tractor

LD1 · Jul 21, 2017

Rustyiron said:
So your doing a "run" in 2wd, then one in 4wd and comparing?

Thats it. Just want to make sure there is some lead. Dont have to be much. Just some that way you arent "plowing" the front tires through the ground.
Basically a lag condition would be trying to make the tires turn SLOWER than if they were just free wheeling.

As long as there is no lag, I dont think we have to get too technical about just how much lead there is, cause I think we can be confident that the lead wont exceed what the OEM setup was with a slightly smaller rear tire.

halfbean · Jul 21, 2017

Thanks for help, it doesn't bind up when switching 2wd to 4wd or vice versa. I looked around and though it isn't in Kubota manual, evidently Kubota sold some 4wd 9540s with the 16.9-34 rears if the center's were cast wheels. I think it will be alright but we will watch it.

CincyFlyer · Jul 22, 2017

There is an SAE tractor tire numbering scheme in which the rolling circumference is classified (I believe it's a simple 1, 2, 3, 4 ...) and that in four wheel drive tractors with different sized tires front and rear (which would be most tractors) you can simply pick any tires that are the same number of classifications in separation. So if you tractor has a 3 and a 5 ag tire set, two numbers different, and you wanted to go to turf tires, and the rear tire you wanted was a 4, you'd get a size 2 front tire to keep the rolling circumference ratio intact, and prevent binding.
I don't know if this standard was ever adopted industry-wide, but if not, you can just measure your existing tires, as suggested, and keep the ratio the same with your new set.