Why rotate tires at all?
A lot of bad information here. Mostly good, to be fair, but tire rotation discussion is like oil brands or oil change intervals or....religion. Seems like so many get emotionally involved in defending what has worked for them in the past.
Tire rotation is to spread unequal rates of wear around so that, basically the tires all wear out at the same time thus ensuring that we get the most out of our money spent on tires. Some vehicles have larger differentials of wear between front and rear tires than others, some wear very evenly. The front of the vehicle experiences larger side forces as the tires are turned, generally tending to "scrub" the tire as well as causing sidewall deflection that distorts the tire and causes wear for that reason as well. This is why we see front tires with edge wear all the time, also part of the reason we run more pressure in the fronts, to minimize sidewall deflection.
Most vehicles, even awd vehicles, tend to show more acceleration type wear in the rear as they mostly only see linear braking/accelerating forces. Changing the type of forces acting on the tire to hopefully wear the tire in areas, mostly sidewall, that it didn't see in the previous position is important but not the only reason we do it.
Cupping is not an alignment concern. It's just not, sorry. Cupping is a pattern that develops when the tire sees wear force in only one direction. Usually this means braking, but not always. Very carefully driven (Think Grandma) front wheel drive cars that don't get tire rotation often have terrible cupping from the rear as those tires see only braking force, and the rear of little cars can almost come off the ground during braking, meaning the tires is more likely to slide during the event, causing abrasion in one direction. Run your hand around a cupped tire in one direction, then back in another. Almost always you will feel rough one way, smoother the other. This wear pattern can be corrected by reversing the tire, I've done it for my customers over the years hundreds of times.
Don't let it get to the point of cupping? Then I don't usually see the need to cross rotate. Tires wearing perfectly even all around? Never rotate...not that this is really possible I'm just illustrating that every vehicle can be different. Some require more frequent rotations to get what we are after, some less. Generally big vehicle like our trucks tend to NOT be as picky (mostly dependent on the driver and how aggressive we are) and can make do with a 10k or so interval between rotations. 5k is pretty extreme but I have customers who request this and their tires wear really well, but they tend to be overly careful people as well and may have habits that help that. Point being it's a moving target not a one strategy fits all thing.
As for the 5 tire rotation, you will get 20% more mileage before you have to replace your tires and that's money saved. Once, if you use an old tire as your new spare when you switch them out. Or spend the money on the back end to replace all 5 and then you also lose all the time/money you spent to pull the spare every time. Not to mention the spare usually looks like crap from being underneath for the last 6 months. I don't usually see the benefit.
