I put one M105A2 on my 20' car hauler back in February. My hauler is 80" between fenders, 20' deck and the M105 tires were 76" outside to outside, so it was close when I went to roll it off. If you are going to load and unload with a forklift, they should fit without a problem as you can arrange them to avoid your fenders.
Another thing I did as a precaution, is to bring a section of 10" channel steel (7'6" long) to increase the width of the trailer if necessary due to the wide variations of tracking width on the M105's. Even with the parking brakes engaged, it was able to hop right out of the 10" channel, so I would recommend 14" as a minimum or utilizing the 10" with some welded plates to hold the tires better.
HTH
Bill