SDT
Veteran Member
Thanks Mathias. I am very confused now after doing further research about swapping out the tires. The tractor came from the factory equipped with bias Goodyear 9.5-24's on the front and the 16.9-30's on the rear, cast wheels all around. If I want to change to the 320/85R20 and 420/85R30 radial tires will that mean new front rims AND re-gearing the front axle? I am new to Kubota and not very experienced with newer (post 70's) tractors. I don't understand why the pizza cutters are so prevalent in the US on these midsize utility tractors.
Whichever tires we end up with will definitely be loaded. I'm not too thrilled about having the tier 4 emissions system either, I would have preferred to get a well kept 7040 but the old man is dead set on a NEW tractor (majority of the money going toward the tractor is his so I can't complain).
To change to the Kubota optional radial tires you will not need to re-gear the front axle but the radial front tires will almost certainly use different front rims. Not sure about the rears but I doubt it.
Generally, rims/tires are swapped as a set (all 4). Tire changes are most cost effectively done before the tractor is ordered. Your dealer may rape you if you decide to do so now. I know that mine would.
Cast rear centers is an entirely different issue. If you did not order cast rear centers (cast centers are available only for rear wheels) you may wish to reconsider. Cast centers add (don't nit pick) 500-600 lbs. to the rear axle vis-à-vis the standard stamped centers without adding width. The cost for cast centers (when ordered) is reasonable. Again, your dealer may rape you if you decide to change to cast centers now.
I ordered my M9960 with cast centers as I never use liquid ballast (I change/repair my own tires.) I also ordered a single pair of rear weights. More weights would have added to the overall width of the tractor as I have my rims adjusted. I also ordered a ballast box. A ballast box is much more effective than liquid ballast, cast centers, wheel weights, etc., when doing FEL work, as it is mounted behind the rear axle and is, therefore, a counterweight. Ballast boxes are not particularly expensive and take up less space than other three point mounted implements sometimes used as counterweights.
SDT