Tractor Tire Size

[Big Orange]

I know 4x4 tire size is important so the question is ratio:
I have searched this site but have not been able to figure out the ratios for my tractor.
I have a 3650 GST 4x4 the previous owner had the following when I purchased the tractor.
Rear: 14.9x24 turf tires (I think these are 1 size bigger than factory)
Front: Regular truck tires 235-85 16 (he says these are matched.)

My question is I also have a set of AG tires for the front they are 8-16 and are bigger than what I have on the front I want to get the tires correct and want to know with the rear turf tires being in good shape but the fronts needing to be replaced and wanting to get more aggressive on the front (I have chains on the rear for snow) what range sizes can go on the front.

More info: I have read about rolling circumference and ratio front to rear but how do I know if that ratio is correct on my 1992 Kubota as not sure was was factory?
Thanks for any help

 

[North Idaho Wolfman]

Your L3650 came with:
Front 8-16 RC= 92
Rear 13.6-26 RC= 147
These are R1 tires
Ratio 1.59

There was an option for Turfs
Front 27x8.50-15 RC=77
Rear 355/80-D20 RC=124
Ratio 1.61

Right now you have
235/85-16 RC=99
14.9-24 RC= 151
Ratio 1.51

The ratio on your tires right now is WAY OFF!
Get it changed before it causes damage if it hasn't yet.

 

[Big Orange]

Now I am confused dose not take much LOL
in all of the forums on tires it says to divide the larger tire into the smaller tire.
So this would give me a ratio when new of .62 and a ratio of .65 now and a ratio of .60 if I put on the AG tires on front.
I used Wolfmans RC values
How close does the Ratio need to be? and do you divide big into small or small into big?

Wolfman (or any one else) do you have the formula to use I want to get this correct

 

[Big Orange]

Still need HELP anyone!!!!

 

[North Idaho Wolfman]

If you put Stock AG tires on the front of it:

Front 8-16 RC= 92
Rear 14.9-24 RC= 151
Ratio 1.64
151/92= 1.64
1.59 x .03 (3% Max) = .05
1.59 + .05 = 1.64
So yes it would work, much closer ration than you have now, but your still pushing the high side of the ratio. 3% is safe, best is 1%

With the way your tires are set now the front is trying to outrun the rear, that is the best scenario, but it's pulling way to hard, about 5% or more than stock.
With putting the 8-16 on the front your going to now have the rears outrun the fronts, not as good of a scenario, but your ratio is much closer, it's at 3% off of stock.
To get back in the right numbers (front out running rear) you would need to change the rears too.
8-12 RC= 92
12.4-24 RC= 137
Ratio 1.48

 

[Big Orange]

Thanks Wolfman I think I got it now, was quite confused by all the postings by tiredguy that have you divide the rear size into the fronts
I have not tried this math yet to see if it works out the same % points.
I just did the math and it works both ways, small tires into big or big into small you get the ratio just keep it the same.

Looks like no 4x4 once the ice is gone until I swap tires, my only saving grace is the front tires are bald and that lowers my RC a couple of inches so its a little closer.