Tires: Dry Rot Tires?, toyota cambry, thanks in advance

Question
Have a 2000 Toyota Cambry; tires replaced app '06; Recently the instructor in my grandson's mechanics class indicated to my wife that the tires had dry rot. Small cracks at edge of wheels. Is this somewhat typical or is this an immediate danger or in between? (normal yrly mileage split between expressway and intown (12,000-15,000 miles yr)

What's the possibilities causing a tire(s) to blow?

Thanks in advance for your help; my wife is scared to drive the car now.

Answer
Jim,

Rubber deteriorates over time and cracking is a symptom that the tire is aging. Small cracks are OK, and cracks do not of themselves cause problems.  Because they are a symptom of a much larger problem, you need to have someone look at the cracking to determine the severity.