What happens to all charge off debts??????

I have "charge off" accounts in my credit reports. I've learnt that after 4 years in CA, the statue of limitation expires, and after 7 years, the negative items disappear from my credit reports. Is it true? If those "charge off" disappear from my credit reports, will my credit appear to be better to the banks? And just curious that if negative items is no longer shown in the credit report any more and if my credit looks good resulting from the disappearance of those negative items, if I go get a car loan, and the car dealer sends my application to the bank that I have charge off account with, what will that bank do?