I saw your post this morning ,I've been at my shop this morning .I have a 1963 M-37 B1 . I measured the pattern It's 4 1/16 inches center to center on the studs . I don't know why the big diffrents in what I measured and what you guy did , but thats what I have. Till Later
That's not the actual procedure for measuring a five bolt pattern. For a five lug pattern, you measure from the back of one hole to the center of the second bolt hole (skip one). This is done as it's easier (and just as correct) as trying to measure from the center of the stud to the point on the circumference where a stud would be...
Measuring from the center of one stud to the center of the one directly accross is used when you have an even number of studs.
Measuring from the center of one stud to the center of the next gives the stud spacing, but you don't need this measurement if you are ordering wheels and can reference the pattern and circle measurement. It is handy if you are looking at wheels/hubs at the junkyard (once again, it's an easy one to measure...).
As I said in my earlier post, my data didn't come from a measurement, it came from the Budd technical (engineering data) from where they manufactured the rims and hubs... It's easier to look it up than to measure sometimes, sometimes it is good to measure to ensure that things haven't gone "funky".
I don't have the "how to measure" page from the Tire and Rim Association Yearbook handy to scan, but a good reasource on measuring is:
American Wheel and Tire - Houston Texas Custom Wheel and Tire Headquarters 2009
Hope that this helps clear up some of the confusion...