I dont believe X style rotating will not extend the useable life of your tires. I dont care what the owners manual shows. They dont design,produce or warranty tires.
It is your right to not care what the owner's manual says.
The original poster read his manual, noted that the stated procedure contradicted what he had "heard a long time ago", and came to us for input.
While the manufacturer, in this case GM, is not a tire manufacturer, they do specify the tires that are original equipment for the vehicle. As such, they are in a position to suggest best practices for the tires that are supplied with the vehicle.
To specificly address the concerns of the original poster, this page from Bridgestone
states that "The 'Cross Pattern' provides the best results and can be performed on any Front or Rear Wheel Drive vehicle equipped with 4 non-unidirectional tires. (Unidirectional tires must be rotated front to rear only.)"
The folks at Michelin, who own the BFGoodrich brand, concur, as shown here
I have always rotated front-back-back-front EVERY 5000 MILES, NO EXCEPTIONS. The majority of people do not rotate tires period. The shop where I buy my tires offers free rotation every 5K. The owner told me that the only customers who complain about tire tread life are the people who admit they don't rotate.
Certainly the concensus is that rotating the tires is better than not rotating them. Nobody has suggested otherwise.
About tire cupping: it has NOTHING to do with rotating the tires, it is caused by bad alignment, unbalanced tires, bad front end suspension components or incorrect (too low air pressure).
Cupping is also caused by worn bearings, mismounted wheel assemblies, and mismatched or inconsistently inflated duals.
While cupping is not caused by a failure to rotate in a particular manner, an x type rotation will serve to minimize the amount of cupping and extend the service life of a cupped tire.
Of course, if someone observes cupping on their tires, they should have their suspension examined and corrected as needed.
Lots of people don't even check air pressure and some that do use those $1.00 pencil gauges that are worthless.
Everyone should check their tire pressure. I'm glad that you do. I wish more people did.
Matching tires and tire pressure to the application is necessary in order to achieve long tire life.
Not only does incorrect inflation cause premature and uneven tread wear, it also results in an unsafe condition.
It is also worth noting that appropriate tire pressure is a function of the load presented to the tire. For a vehicle with a nominally uniform weight distribution (my Honda, for example), having all four corners at the same pressure is correct. For my truck, however, while it is empty I run the front tires at a higher pressure than the rear because the front of the truck is heavier than the rear. When I plan to work the bed or otherwise load it substantially, I add air to the rear tires.
Everyones got thier perfect method, I personally would have a hard time remembering which direction in the x to go on every vehicle every 5k miles, I dont plan to start making sketches.
I'm glad you are satisfied with the results of your procedure.
Like you, I have a hard time remembering which direction in the x to go, and am unwilling to make a sketch for each of my vehicles. However, I don't have to make such a sketch. I get the owner's manual out each time I rotate my tires. I have to, because the manual is on top of my tire pressure gage.
There are many discussions about tire rotation, here and in other forums. Many people still believe that an X rotation will cause the tire to fail. They believe this for the same reasons that the original poster did, specificly because "[someone] told me this" ... "a long time ago."
A long time ago it was true, however tires made with a current manufacturing processes don't suffer from the same limitations that their predecessors did. Tire manufacturers recommend an X pattern for tires that do not have a directional tread. For tires with a directional tread, they still recommend a front-to-back rotation, indicating that some rotation is better than none.