By "cold rating", do you mean the maximum pressure stamped on the side of the tire, or the recommended pressure labeled on the car?

I've got over 400,000 miles experience inflating to sidewall maximum and have had far fewer failures than I had in 200,000 miles inflating to the car's label's recommendation. This includes extensive driving during RI's 0 degree winters and 95 degree summers.

As for exceeding the sidewall stamp, I'm not so confident in that idea. I have read some credible stuff suggesting that it is quite appropriate sometimes, but I never purposely do it more than a few PSI.