opiate painkillers safe dosage question

I am tolerant to opiates, have been taking them almost daily for around 4 years in the form of norco (10 mg hydrocodone) and oxycodone instant release 15 or 30 mg pills

I have tolerated doses up to around 300mg/day.  my tolerance is currently not quite that high though

my question is, if I am tolerant to opiates then is it safe for me to take them daily and not worry about the chances of accidental overdose?  assuming no alcohol or other drugs are combined, how large of a dose would someone like me need to take for it to be dangerous?  I currently take about 60mg hydro and 45mg oxy/day with no problems .i take the pills orally..  i know everyone is different but I have heard it is difficult for somoene to have a dangerous overdose to a pure opiate agonist by itself if no other drugs are present and the person has a tolerance. is this true? how big of a dose would be considered dangerous for someone at my tolerance level?

[Burton Dunaway, PharmD]

There is no chart or formula to determine what dose of opiate will cause an overdose in a certain individual, but it is very unlikely that a person will overdose from taking a steady dosage of opiate or gradually increasing the dosage. Overdoseage can occur in anyone who takes significantly more medication than their body is used to, or mix the opiate with alcohol or other medications.