Tires: Tire Pressure, wheel drive car, nissan altima

Question
Hi Barry
I appreciate your input and will folow your advice on tire rotation. I have another question about tire pressure. I'm very diligent about checking and maintaining the correct pressure. I check my tires about every two weeks.  I check and set them cold in the morning. I live in Southern California and on any given day during the winter, morning temperature is anywhere from 39 to 48 degrees and daytime temperature anywhere from 65 to 80 degrees. In the summer, it can go from 60 to 100 degrees. Given that tire pressure changes about 1lb for every 10 degrees of tempurature change why would you set the same level of pressure for winter and summer. If I were to set them when it's 60 degrees and check them again when it's 40 degrees they will appear to be 2lbs under inflated even though at operating temperature they would be set correctly. Or I'd have an over inflated tire if I did the opposite. Your thoughts would be appreciated.
Thanks
Tony

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Followup To
Question -
I have a front wheel drive car and the most recommended rotation pattern seems to be the forward cross pattern i.e. fronts to rear and rears crossed to front. But the owners manual on my Nissan Altima recommends front to back and back to front (same side of car). I also saw this recommendation on your website.
I'm confused about this since it would seem that moving the tires to all four corners of the car over the lifespan of the tire would even out wear and prevent the tire from being exposed to the same wear factors. I thought front to back only applied to unidirectional tires. I'd appreciate it if you would explain in more detail why front to back is best.
Answer -
Tony,

Obviously I disagree with the Nissan's owner's manual.  But I suspect what is going on is that Nissan hasn't reviewed its recommendations for many years and still retains the old pattern.

In the early days of radial tires there was a problem and keeping the tires on the same side was better for durability.  But those days are long gone.

IMHO, the "Modified X" pattern (what you described) is the best pattern for the exact reasons you stated.  The only modifictaion to that would be that if there is a full size spare, include it in the pattern.....AND... if you have staggered or directional tires, the pattern obviously has to be different.

Hope this helps.  

Answer
Tony,

If you are racing, then differences of a few psi can make the difference between winning and 5th place.  But on the street, close enough is close enough.

I would err on the side that generates the most pressure.  So setting the pressures on a cold morning makes the most sense.

And all inflation pressures are "COLD" except when they specifically mention pressure build up.

Now let's talk about the starting pressure and what happens as you drive.  Obviously, the tire heats up, and so the inflation pressure goes up as well.  Since the amount of energy being consumed is the same (assuming everything else is the same!), then it doesn't matter (much) what the ambient temperature is when you start off, the temperature (and pressure) build up will be the same.

If you wanted to be really technical, it's the highest temperature that's important for tire durability, so a little extra pressure in the summer would be a good thing.  Hence my thought on cold mornings.

I would not worry about overinflated tires, except to say that you don't want to be more than 5 psi (cold) above the placard inflation, and you don't want to see more than 5 psi buildup.  If you do see more than 5 psi buildup, then you need to either increase the starting (cold) inflation pressure, or use a large capacity tire.