Why do you guys go to 265/75-16 rather than 245? The difference in width is only 20mm, hardly noticeable and more costly.

Also what is a good psi cold, 30 degrees f, assuming no weight other than truck?

They fill the wheel wells and look better than the stock pizza cutters. Call me vain but that's the only reason I put them on my truck. 285's look even better, 265's go on a stock truck with no clearance issues.

Looks better and 400lb extra load capacity, of course your wheels need to support the load.

265's are about 1 inch taller than 245's.

265's, so I don't look like I'm rollin' on 4 compact spares!:D
Empty or light towing, I run 45psi front, 35-40psi rear, for traction purposes in the winter. Summer, I run 55-60 front, 45 rear, for better mileage and tire life.

The 265 is 20mm wider and in a 75 series tire it is 75% of the 20mm taller.

equals 15mm taller
In short the 75 series tires are:

245 is 9.6 inches wide and 30.4 tall

265 is 10.4 inches wide and 31.58 tall

285 is 11.18 inches wide and 32.76 tall

of course some companies will vary slightly
remember the stock rim in most cases is 6.5 inches wide