Slick 60's

So I'm digging around in my copy of the 1961 Ford Truck Operators Manual and I come to a section listing all sorts of specifications.

Among them is a Load Capacities chart.

For the F100 are the following Maximum Gross Vehicle Weight and the next column front tire sizes.

2 Wheel Drive

4,000 - 6.70 x 15
4,400 - 6.70 x 15
5,000 - 6.50 x 16

4 Wheel Drive lists the same weights and size but has an addition line:

5,600 - 7.00 x 17.5

The rear tires sizes are all the same as above, but are followed by an S

On to my questions.

What's the S stand for?

Do all the wheel sizes have the same bolt pattern, and if so, would they all fit on any 1961 F100?

.

The "s" is for single, the "d" for dual. The dash indicates the ply rating, and in those days, the actual plies of construction. Note also that there is no reference to tread plies as opposed to sidewall. These were all bias ply tires.
Yes, and yes; the 17.5" wheels originally were on vehicles with the large radius fenders, but it is my experience they will work with the listed tire sizes even on the reduced radius fenders normally found on the 2wd F100's.
Paul