Hi,
I saw your post this morning just as I was leaving the house. Hope I'm not too late to help. I had one like that; a 1991 MTD with a 12 HP Briggs.
Do your wheels have two bolt holes (3/8" ?) straight across from each other and only a bolt and washer at the end of the axle shaft? If so, you can use a H/Freight wheel puller kit # 62620 (Pittsburgh line). It is a real nice puller kit and VERY cheap. Put a short bolt, no washer, into axle to protect the threads. You will have to use an electric impact wrench and be patient. Keep both ends of the wheel tube sprayed with penetrant It says not to use an impact wrench, due to thread galling, but you will HAVE to. Keep the large puller plate bolt threads & plate threads covered with anti-seize liberally....often. When I was done, the puller bolt and plate threads were still just like new. I rattled away for a day and a half [on and off of course] 1/8" to 1/4" at a time. If you try to do it manually, the long bolts will twist sideways and it all falls apart. You'll have to get a few longer bolts as the wheel starts coming off. The wheel tube is pretty deep. As the axle shaft starts disappearing into the wheel tube, you'll have to cut a few different lengths of shaft steel just a little smaller diameter the hole in the tube. You may be able to get by with just stacking a few nuts on top of each other 'til it comes off. I was NOT the lucky! Mine was a total bear......inch by inch ALL the way out.
Ohh, Important. Re: The two 3/8 holes in the wheels. To reinforce the backside of the wheel, you'll have to use thick large washers or plates between the nut and the wheel. Otherwise, just the nut and one washer will definitely damage the wheel.
Very best of luck to you.
Mike