A friend has 180/85D12 tires on the front of a Kubota. That size is hard to find. The info I get for that size is 24.1" high with a rolling circumference of 71. He has found tires in size 600-12 that are 23" high with a rolling circumference of 69. Would it be OK for him to use that size for the 2 fronts or would it mess something up on a 4x4 tractor?