260 inch wheelbase 53ft trailer.

Unless the rules have been recently changed, in order to be legal to run in all provinces, and likely states as well, pulling a common 53' trailer, the maximum wheelbase would be 244" to keep it under 23 meters, which is 75.5 feet, which is uniform on most of the continent.

A deeper king pin setting would let you run a longer wheelbase, but it puts the trailer closer to the bunk with a greater swing radius.

You could have a longer WB, but you have to pull a shorter trailer.

You could slide your 5th wheel ahead and put more weight on the steering, but you shouldn't have to do that unless there was an error in loading.
Makes no sense to run with all that extra weight on the steering all the time on the highway, puts a lot of extra heat in the steer tires.

So the definitive answer is, if you intend to travel coast to coast, Canada and USA with a minimum amount of dicking around making adjustments to comply before entering a scale and trouble you might have from various agencies, the wheelbase you need is 244" or less.

 

I agree with this

I agree with this. It dose look like they changed the rulles recently and for manatoba as early as Feb 15 but if you pull a 53 ft trailer it makes no sense why you would want more than 244 also it said when you are running a 6.2m 244inch wheel base your semi trailer wheel base can't me more than 12m when you go all the way up to a 7.2 m wheel base which is 284 inch your semi trailer wheel base can't be more than 11.87m which means your trailer wheels need to be shoved up aswell. Some guys say a longer wheelbase rides a little better but with the new suspension systems on trucks I dont see the need. Also if you get in a tight spot longer wheelbase would not be as easy to get around with. If you pull a van or refer you would have a large gap between the sleeper and trailer there for killing your fuel economy there's just to many draw backs to a long wheel base when your limited to 23 meters long