Tires: Nitto tires defects, highway traffic safety, traffic safety administration

Question
I have Nitto tires (NT420S-1 295/35R24 11OH DOT CXBY A560807 and NT420S-2 295/35R24 11OH DOT CXBY A563806) on my 2009 Escalade. I have already had to replace 2 since purchase (9/11/2009) due to "severe splitting" of the outer edge. I currently awaiting the replacement of two more due to the same problem. My service advisor says he has never seen this (nor has the tire manager)occur. Is this a fluke or an ongoing problem with other Nitto tires?
Thank You, Lori O.

Answer
Dear Lori,
It is difficult for me to assess the splitting that you describe without seeing it.  I have researched complaints or recalls for this tire on the National Highway Traffic Safety Administration (NHTSA) web site but could not find any.  You or your service advisor have the option of contacting Nitto Tire, I show their number as: 888 529 8200, nittotire.com
I do have some concerns about this 24" fitment on your Escalade after reviewing the original equipment tires for the 2009 model:
Depending on which '09 Escalade you have, the driver's side door placard would have recommended either 30 psi (front and rear) for your original tires, or 35 psi front and rear.  The Nitto 295/35R24 requires a MINIMUM of 42 psi all around to carry the equivalent load of the original tires (you can get back to me to confirm your original tire size).  If your tire installer did not inform you of this higher air pressure requirement when the 24" tires were installed, and apply at least 42 psi, I fear that your tires have been significantly under-inflated...perhaps explaining the damage that you are now describing.
Don't hesitate to contact me with further questions.