How did Buick measure wheel width?

[Dynaflash8]

I AM LOOKING FOR ONE WHEEL FROM A 1941-1959 BUICK ROADMASTER SERIES 70.  It is to fit my 1941 Buick Roadmaster.  PREFER HUBCAP CLIPS, BUT NOT NECESSARY.  I DO NOT WANT A 15X6.5 WHEEL.  I don't know what they fit, but that begets the question, how do you measure the wheel?  Or, better yet, how did Buick measure their wheel width?  According to the Buick Master Parts books (1947-1953 and 1960) the same 15-inch wheel fits all of the Roadmasters (and Century's through 1942, as well as short wheelbase 1941-42 Specials).  The book says they measure 6-inches wide, i.e. 15x6.  My mechanic says the machine measured four of my wheels as 6.00 inches wide outer edge to outer edge.  That would have been using that plastic thing they use when spin balancing.  One measured 8-inches wide.  Go figure.  Buick changed the tire size in 1947 or 1948, but apparently not the wheel size.  I always have heard 1941-42 wheels were different, but according to the parts book not thinner or wider.  The 16-inch tires on the 40-50 series were 6.5-inches wide.  So based on that, I am now just looking for a 15-inch Buick wheel 6.00 inches wide edge to edge, if there is really such a thing.  I know the wheels on my car are not 1941 wheels, but as of now the only difference I could determine was that original 1941 and I guess 1942 wheels only had three clips.  If anybody has a decent 15x6 wheel I need one, preferably with clips, but clips are available and I have two or three on the shelf myself.

[1939_Buick]

" how do you measure the wheel?" 

Same as others I assume. The inside of the rim

 

https://www.gemplers.com/tech/tires-measure.htm

 

http://www.carbibles.com/tyre_bible_pg4.html

 

https://www.lesschwab.com/learn/article/choosing-custom-wheels-is-about-more-than-good-looks

[Bloo]

49 minutes ago, 1939_Buick said:

" how do you measure the wheel?" 

Same as others I assume. The inside of the rim

 

Exactly. The rim width is where the bead sits, and you need a tire off to measure it accurately.

 

19 hours ago, Dynaflash8 said:

My mechanic says the machine measured four of my wheels as 6.00 inches wide outer edge to outer edge.  That would have been using that plastic thing they use when spin balancing.

 

Those are only a close guess. It's purpose is to tell the balancing machine how far the weights will be apart. It would make sense for it to measure the actual distance, but as I recall the one I have is compensated, and measures something close to actual rim width, at least on steel wheels. It would read a little high on aluminum due to the extra thickness of the metal. The plastic thing touches the outside of the bead surface. The outside edge of the rim hangs out even further, and is usually not very consistent.

 

It is hard to guess what they might have measured. If they truly measured to the outer edge, you probably have 5 inch wide wheels. If they just did it like they were going to balance a tire, then they are probably 5 1/2 or  6 inches.

 

For what its worth, I was measuring some 1936 Pontiac wheels yesterday, and they match the book at 4 1/2 inches wide. They measure 5 3/4" at the outer edge of the lip, and so gained slightly over an inch when measuring that way. I would expect similar results on the Buick wheels.

 

 

 

 

Edited January 23, 2018 by Bloo (see edit history)

[Dynaflash8]

6 hours ago, Bloo said:

 

Exactly. The rim width is where the bead sits, and you need a tire off to measure it accurately.

 

 

Those are only a close guess. It's purpose is to tell the balancing machine how far the weights will be apart. It would make sense for it to measure the actual distance, but as I recall the one I have is compensated, and measures something close to actual rim width, at least on steel wheels. It would read a little high on aluminum due to the extra thickness of the metal. The plastic thing touches the outside of the bead surface. The outside edge of the rim hangs out even further, and is usually not very consistent.

 

It is hard to guess what they might have measured. If they truly measured to the outer edge, you probably have 5 inch wide wheels. If they just did it like they were going to balance a tire, then they are probably 5 1/2 or  6 inches.

 

For what its worth, I was measuring some 1936 Pontiac wheels yesterday, and they match the book at 4 1/2 inches wide. They measure 5 3/4" at the outer edge of the lip, and so gained slightly over an inch when measuring that way. I would expect similar results on the Buick wheels.

 

 

 

 

So Bloo, it appears that tool would measure to the bead, but the wheel turns over to the outside on the edges.  Do you believe that if the wheel was measured to those outside edges it would appear to be as much as 6.5 inches?  I don't think they turn out a 1/2 inch on each side but maybe they do.  OH SORRY BLOO, I DIDN'T SEE THE SECOND PART OF YOUR MESSAGE:  YES, THEY PUT THAT TOOL ON THE TIRE UPSIDE DOWN, SO THAT ANSWERS THE QUESTION.  And thanks by the way.  I think you just about told me what I need to know.  Appreciate your response.  Earl BCA #55

Edited January 24, 2018 by Dynaflash8 (see edit history)

[Bloo]

Whatever that wheel is, I hope you find one!