Not that I don't think the tire pressure could be up'd by a point or two, but I'm going to agree with Brian_MP5T, not just because it makes sense, not just because manufactures stand to gain nothing if our tires just wear constantly since they aren't making money they can count on from it and thus probably aren't leading you on, but because I used to have a light quick (not fast) car that was fun to drive at the limit, and it was WELL BELOW the limit, when I was fully comfortable with my 4.5lbs-over-inflated tires that I went to turn a 60km bend at 40 in the rain and the car just never turned, sliding me off the road, readily cutting down both front tires, and narrowly missing a tree. My Car was lowered, so guess how much extra damage it did.
It's true that increasing tire pressure has some benefits, but don't forget that in inclement weather, the benefits are few, and in addition to that, the tires are wearing with use. This means that when they are new, you're probably fairly safe even over inflated, but as those tires wear, the unsafe-factor increases exponentially instead of gradually (the way they would if you had them at recommended tire pressure) ..which is what allows ppl to drive on the tires long beyond the recommended switch-frame and still get away with it.
The gains in fuel economy and steering feel are great, but car control decreases, and with wear, the chances of unexpected occurrences ramp up fully. There are a ton of other methods and techniques to save on gas where if you get them wrong, you'll be safe to try again. Over-inflating tires isn't one of them.
Imagine this, it might be a sweet race strategy to overinflate the tires a bit and run longer than everyone else..walking to the checkered flag... yet there's a reason that this is never done. Safety first right?
Like I said, likely no harm in going over by a couple.. but there isn't a lot of benefit that comes from a couple over... the big benefit comes typiclally from +4 and up... i used to do this. (peep)
