If I could ask, what size and brand of front tires do you have? I have BFG T/A Radials 155-80R-15 that are 24" tall on 4" wheels and they seem like there is too much weight on them even though I slightly over inflate. You now have a heavier engine than me and your tires don't look that way.
Counter question after your question:
Are the centers of your front wheels as far forward as his appear to be in the image directly above?