Why do they say not to put chains on front?

Cause the xterra did awesome with them today just on the front. MUCH better then just on the rear. I was going everyhwere. Even in a place where a fronty got stuck with them on the rear. We swapped them up front and he went right up.

More weight on the fronts? The front brakes do most of the work? The front wheels steer the vehicle?

Just guesses. Never had a chance to try it either way, myself. Only time I came close is when I had a front-wheel-drive car and put chains on the fronts (duh) to get around back in college when I was delivering pizzas.

There's less wheel well clearance up front, maybe that's why?