Tires: dealer swapped tires?, midas store, 4 digit numbers


Question
My fiance recently took her car into the dealership to have an oil change and tire rotation completed. After the oil had been changed, the mechanic told her that she needed 2 new front tires. She felt that it was too early to need tires so she refused.
When i arrived home from work I could tell right away that the tires on the front were not our tires.
I had the local midas store measure the tread depth. The rear tires were at 10/32" and the front 2 were at 2/32".
The mileage on the car is 37,500 miles.
The car was serviced in April (31,500 miles) and the tread depth on all 4 tires were measured according to the dealer at 7/32" or greater.
I also have photographs from an insurance claim when the car had 33,000 miles. The tread design on the rear tires then match the tread on the front now. Oh, by the way, the front tires have a manufacture date of 0906 and 0806 and the rears are 3307 and 2907. So they have different treads but are the same make and model. If they did indeed rotate the tires this past time, that would mean the rear tires are now in the front at 2/32". Meaning the rear tires wore approximately 5/32" in 6000 miles.
Normally you would see the tread go down more on the front, not the rear.
The GM of the dealership said "I'm confused on what you want us to do about it." I told him I wanted my original tires back, these are not the same tires i had when i came in there.
They gave me the serial/DOT number for 2 tires that were placed on the car when we bought it.
The 4 digits that signify the week/year match on only one of the 4 tires. The sales advisor there said the week/year are the same on both tires (not true) and then he gave me an additional 4 digit number after the week/year number and said that this number was unique and would be different than any of the tires I have on the car.
I'm not sure where this 4 digit number is. The number he gave me does not match any of the 4 digit numbers I could find on the tires.  I'm guessing this is the mold # above other numbers on the sidewall.
Do you think I have enough evidence to have my tires replaced for free? The dealership sells the exact same car as mine with the exact same tires/wheels (they re-sell the rental fleet. Is it possible that those rear tires wore down that fast? All five mechanics and tire stores i have talked to have pretty much sided with me in the feeling that it was next to impossible to have that much wear. I'm not sure what the additional 4 digit number is...if it's what i think it is, the tires don't match what they claim.
I'm under the impression they took our tires off our car and swapped them with a rental car on the lot or someone else's. Could be an honest mistake, but I'm afraid it's the alternative. Your thoughts?


Answer
Brian,

There are bits and pieces of information that are either missing or do not make sense.  So if I were a judge, here's what I would want to know:

What was the date of the manufacture of the vehicle?  It ought to be on a sticker on the door frame.

This date should be after the manufacture date of the original tires.  If any tires have a date code later than that, they were not the original tires and if any of the tires have a date code just before that date, then there are probably the original tires.

BTW, Some tires do indeed have unique number on them.  Can you find a white bar code on the tire?  But I am under the impression that this is not recorded anywhere to connect it to the vehicle.

So here's the scenario I see:

Since we can't be sure about tire rotation, we should ignore the positioning of the tires on the vehicle and concentrate on identifying the tires as pairs.

The vehicle was purchased used (date and mileage are important, but not stated in your commentary.) and a pair of new tires were placed on the vehicle at that time.  The tires applied at that time are probably the mid 2007 date coded tires - and I'm guessing the dealer confirmed one of those as correct.  As a judge I would assume the mechanic was just sloppy and assumed the pair of tires had the same date code.

BTW new tires generally have 10 or 11/32nds tread depth new.

I'm also going to assume the early 2006 date coded tires line up datewise as possible original tires to the vehicle.

The dealer measured the tires at 32,000 miles at 7/32nds. This doesn't make sense!  The pair of tires ought to have different tread depths.  

The photo you have at 33,000 miles shows tires that are identical in pattern, but have different depths.  This completely contradicts the tread depth measurements taken at 32K, so we should completely ignore that measurement.

At 38,000 miles the tires are now at 10/32nds with a mid 2007 date code on the rear (this might make sense for tires applied at the time of purchase), and 2/32nds with an early 2006 date code on the front (which might make sense for tires original to the vehicle).

So I don't see enough evidence to conclude that there is wrong doing on the dealer's part.  As a judge I would conclude that you didn't prove your case and further that there is sufficient evidence to say the dealer probably didn't switch the tires - that the tires in the photograph are the tires on the vehicle now!!

As a reality check, it is extremely unlikely that the dealership would have a set of tires lying around with just the right size and just the right pattern and just the right date code to match up to the vehicle - and he certainly wouldn't put newish tires on!  So if the date codes of the tires line up, the only thing you can conclude is that the dealership did not switch the tires.