Tires: How to check for tread seperation, goodyear tires, tonka toy

Question
My son has an Iszu truck that I call a Tonka Toy. Anyway it has a very bad waddle that is noticable at very slow speeds and gets much worse as speed increases. I think it is tread seperation on multiple tires but I can not detect it by sight. How might I check for tread seperation. The vehicle is undrivable so we cannot drive it to a shop. Do you have any suggestions to check for this without removing all tires and taking them to a tire shop. They are Goodyear tires that he bought from a wrecking yard and came from a totaled jeep. My son has driven these tires for at least 2 years and the problem has gotten worse over time until now it is not drivable.

Answer
Gary,

First, tread separations can be dangerous so you should avoid driving at high speeds on them if you suspect one.  However, slow speeds (say under 30 mph) are OK in that if the tread starts to come apart, you will know it and can stop quick enough to avoid the potential damage a flopping tread may cause.  So you might consider doing that.

First, tread separations will cause a vibration that gradually gets worse over time - in about a couple of hundred miles.  If it's been over several thousand miles then it is probably not a separation, but irregular wear.

Tread bulges are also an indicator, so run your hand over the entire surface of the tread (Use a glove!) and feel for an isolated bulge.

Also an isolated wear spot near the shoulder about 8" long is also a good indicator.

Plus, old tires are increasingly being cited as problems:

Recent bulletins from the tire industry indicate that tires degrade simply due to time.  The age of a tire is important even if the tire is unused.  There some disagreement over how to best express this age limitation, but my take is:

If you live in a hot climate (AZ, CA, NV, TX, and FL) then the limit is six years.  If you live in a cold climate (MN, ND, WI, MT, etc), then the limit is 10 years.  States in between are  ..... ah ........ in between.

Here's how to tell how old the tires are:

First locate the letters "DOT" on the sidewall of the tire.  Nearby will be the DOT code.  DOT codes are 10 to 12 digits long.  BTW the digits can be numbers or letters.

The first 2 digits are a code for the manufacturing plant.  

The next 2 digits are a code for the tire size.  

The next 3 or 4 digits are a code for the type of tire.  

The last 3 or 4 digits are the date code.  The format is week/week/year/year or week/week/year.  These are always numbers.

Starting in the year 2000, the date coding used was 4 digits.  That means the largest number you should see for the year is 09.  Before 1999 the format was 3 digits.  1999 and 2000 are transition years, so you will find both 3 and 4 digits.

The date code only has to be on one side – and it is permissible for there to be a partial DOT code, so long as one side has the complete code.