B7100D Tires


New member

B7100 FEL, and backhoe
Jan 18, 2010
Cohasset, MA
I have a B7100D (manual xmission) and I need new rear tires.
Started to do the research and I have found that the recommend tires
are either:
6-12-2 Front
8-16-4 Rear.

Turf (moderator may want to put these up on the spec page)
20.5 x 8.00 -10 Front
19 x 12.00- 15 Rear

I understand that it important to keep the size ratio between the front and rear the same so you don't mess up the 4WD gears.

So I go to the Firestone Web site and find the rolling circumference of these tires and calculate the ratio

AG Front 69
AG Rear 93
AG Ratio R/f = 1.35

Turf Front 60
Turf Rear 86
Turf Ratio R/f = 1.43

Reasonably close I guess. Now the interesting part.
When I got my tractor It had turf on the rear and ag on the front
That a ratio of 1.24 Oops but I have been running it for 8 years like that.

guess I better get closer to 1.4

So my question. Does anyone know the actual gear ratio?? I can't find it in the specs.

I need new turf tires on the back and don't really want to replace the front tires and wheels.

Any tried putting 31 x 13.5 - 15 on b7100 ?? Looks like it will fit on my 10" rim and would have a ratio R/F of 1.35


New member

B3030 HSTC,B2781 51" front mounted snowblower,60" MMM
Jan 21, 2010
northern lower Michigan
I posted a reply on a thread above yours regarding how to figure out what's needed titled Truck tires on a B7200.
Should help you.