Problems with 2005 Suzuki Reno TIRES

I woke up to find my tire was completely flat about a month and a half ago. the problem according to the auto shop was a bad valve stem, which i had to get replaced. since then i have had all of the other tires on my car leak air to the point where they had less than 5 pounds of air left in them. i went back to the same auto shop and had to replace the last 3 valve stems on my remaining three tires. the time frame involved here was 4 valve stems replaced, one for each of my tires in a total of a 2 month period. *tr

Tl*the contact owns a 2005 suzuki reno. while driving 10-15 mph, the contact drove over a nail and a tire flattened. the vehicle has carlisle, size 195/55r15 tires. he does not know if the tires were the original or replacement tires. the tires were inspected and it was determined that all four needed to be replaced. the contact replaced the two front tires at that time and plans to replace the rear tires soon. other than the internal and external sidewall fractures found on the tires, black rubber residue was also found on the inside of the tires. he still has the tires and can take pictures. the current and failure mileages were 32,000.