The Kubota M6121 tractor tire size is front 320/85R20 and rear 460/85R38. Other tire setup data found for this model includes Front 9.5-24, Rear 14.9-28; Front 540/65R28, Rear 650/65R38; Front 650/65R38, Rear 540/65R28, so confirm the wheel option before ordering.
Front tire320/85R20
Rear tire460/85R38
Front/rear setupDifferent front and rear tire sizes
Tire pressure30 PSI
Rim diameter20 in front, 38 in rear
Ballast35 gal
Other setup foundFront 9.5-24, Rear 14.9-28; Front 540/65R28, Rear 650/65R38; Front 650/65R38, Rear 540/65R28
Kubota M6121 Tire Size Details
Front tire size
320/85R20
Rear tire size
460/85R38
Front/rear setup
Different front and rear tire sizes
Other tire setup found
Front 9.5-24, Rear 14.9-28
Replacement tire size
Front 540/65R28, Rear 650/65R38
R1 ag tire size
Front 650/65R38, Rear 540/65R28
Front tire construction
Metric radial
Rear tire construction
Metric radial
Front section width
320 mm
Rear section width
460 mm
Front aspect ratio
85%
Rear aspect ratio
85%
Front rim diameter
20 in
Rear rim diameter
38 in
Approx front overall diameter
about 41.4 in
Approx rear overall diameter
about 68.8 in
Tire pressure
30 PSI
Loaded rear tire ballast / fluid capacity
35 gal
Tire Size Comparison Chart
Front rim diameter comparison
This model
20 in
Average
24 in
Low
16 in
High
38 in
Rear rim diameter comparison
This model
38 in
Average
38 in
Low
28 in
High
54 in
Benchmarks use typical low, average and high rim diameters for the utility / row-crop / large ag tractor category, not scraped low/high outliers.
Kubota M6121 Extra Tire Notes
Tire size note
The Kubota M6121 uses different front and rear tire sizes in this data: front 320/85R20 (20 in rim, 320 mm width) and rear 460/85R38 (38 in rim, 460 mm width)
Multiple setup note
This data has more than one tire setup for the Kubota M6121. The main front/rear listing is Front 320/85R20, Rear 460/85R38. Other setup data found: Front 9.5-24, Rear 14.9-28; Front 540/65R28, Rear 650/65R38; Front 650/65R38, Rear 540/65R28. This usually means different wheel, axle, turf/ag/industrial, or market options rather than one universal tire size
Pressure note
For the Kubota M6121 with front 320/85R20 and rear 460/85R38 tires, the pressure values captured in the answer are 30 PSI. Tire pressure is load-dependent, so use this as a reference value rather than a universal setting
Ballast note
For the Kubota M6121 rear 460/85R38 tires, the ballast figure captured in the answer is 35 gal. Liquid ballast capacity can change by tire brand, fill percentage, wheel setup and ballast fluid type
Official information note
Mistakes do happen. Tire sizes can change by year, axle, wheel/rim option, tyre brand, tread type and local market. Please check the tire sidewall, operator manual and official kubotausa.com website for official information.
