Out of your choices, I'd go MXand stick with the stock 275-40-17.

 

It's looking like that's what I'll do. I take it the extra 10mm probably isn't going to make a huge difference anyways.

 

You'd have slightly taller sidewalls that'll flex more. I see no benefit to the taller tire.

 

Exactly, I was wondering if that trade-off was worth getting the extra 10mm width, which in turn has a larger contact pathc to the ground for striaght line stuff. I doubt it'd be noticable though, where as the sidewall flex will.