I tokk a guestimate with a tape measure from the rear and thought it was about 64". Good luckCT225/30/35 are all the same chassis. My CT225 is right around 62.5" depending on what part of the curve of the sidewall you're looking at. I wouldn't go any narrower than a 64" (if there is such a thing) blower to cover the back wheels.
-rus-