6-12 vs 6-12B tire sizes?

AaronB

New member

Equipment
B1750D, Rotary Mower, Box Blade, Tow Bar
Jun 21, 2018
1
0
0
Banks. Oregon
I'm trying to find out what size of front tires I need for my B1750D (MFWD 4WD.)

Can anyone tell me the rolling circumference or diameter for the stock Kubota tires so I can find suitable replacements. The workshop manual lists several configurations of "Farm Tires" for my model: 6-12B on the front matched with 8-16 on the back, or 6-12 on the front with 9.5-12 on the back.

My back tire appears to be an 8-16 configuration (markings worn off so I had to measure) so I believe I need 6-12B tires for the front, but finding anything listed as a 6-12B has completely eluded me.

I can't trust measuring my existing tires as the previous owner appears to have replaced the front wheels/tires with 5-16s on 4 inch rims that far as I can tell are about 2 inches less in diameter than a regular 6-12. I also am not sure I can trust a random example of a tire to match the original size as I've found the listed diameter of an 8-16 can differ by (so far) about 2" (29.5" to 31.3".) My rear tire came in around 30" outer diameter.