There are a variety of wheel arrangements that have been applied to the combines, hard to know without further details. Interestingly enough, the TR98 parts guide shows only 24.5 or 30.2 singles available. The TR99 shows a Dual option.
Take a look at the dual and axle setup. If there are no spacers in the system (either between the axle and final drives, or final drives and rims) then no. The TR99 parts show a axle extension for duals, but my guess is you can't remove them without the tires hitting the combine.
6 row heads were not made for duals--see if you can't find a set of 30.5-32 tires and rims instead. If you do, make sure to get the spacers on the rim too.