Everyone that says it's a bad idea is RIGHT!. In addition to what they've told you, consider the effect of putting the smaller diameter tires on the front. You've now changed the ride height of the vehicle and that changes all your suspension angles. The front end will ride lower to the ground. If you're set on doing this, you'd be better off keeping the original sized tires on the front--of course, smaller tires on the rear will also screw up your alignment.
Here's an article on tire placement:
Replacing Two out of Four Tires
You should always have the tires with the most tread on the REAR wheels in a front wheel drive vehicle. The extra tread prevents spin out in turns.