Here are specs for that
B3200
TractorData.com Kubota B3200 tractor dimensions information
This question of mowing on steep hills comes up a lot on TBN. Here's my take on rollover stability.
My 1964 MF-135 diesel has a squat setup for orchard work. The rear axle centerline is 20" high and the distance between the outer walls of the rear tires is 83", which gives an 83/20= 4.15 aspect ratio.
It would take some doing to roll this particular 135 unless your hills are exceedingly steep, in which case you should probably forget about mowing with a standard tractor.
When you go tractor shopping, take your steel tape along and measure these dimensions. Anything much below 3.5 AR to me is getting tippy.
But like a lot of things in life, it's different strokes for different folks. Last year I bought a 1951 Farmall Super A with a belly mounted sicklebar mower. Axle height is 20" and tire width is 63" giving an AR of 3.15. The seller works for CalTrans and this tractor was used for highway mowing including steep sections near overpasses. He told me that he never rolled that Super A, but came close several times.
Since rollover is a safety concern, I would give it top priority when you are looking at tractors.