Recently aquired b2400 with original turf tires on rear sized 33x12.50x15 and replaced front with a chevron type tread 23x8.50x12. Would like to replace both sets with r4 tires and local dealer can't seem to located them in the parts manual. Apparently they must have different rims than came with the turf tires. They don't have any listing for the r4 for that year ('99) however that sales literature shows several tractors with the r4's installed. Any ideas would be appreciated. Thanks.