German tire/wheel size

[Dave_Watts]

Hi all,

Everyone will agree that 760mm is the outside size of a German WW1 fighter tire, (like for the Fokker D.VII).

What I am interested in is the inside size of the tire.

I have a copy of the original Fokker factory drawing for the Fokker D.VII wheel from the Vienna archives, but it has some problems.

It shows the overall wheel diameter as 572mm.

It shows the inside diameter of the wheel as 546mm.

It shows the rim height as 28mm, (this is where the tire goes in and the spokes attach, we'll call it the tire "channel"). *The metal is shown as being 2mm, so the tire "channel" is 26mm.

Here's the problem.

546mm + 56 (28 X 2) = 602mm, not the indicated 572mm. *???

If we go the other way,

572mm - 56 (28 X 2) = 516mm, not the indicated 546mm. *???

When I measured similar type rims, their tire "channel" appears to be about 30mm, so I believe this dimension of 28mm to be correct.

On the drawing, (and similar wheels), the tire appears to rest inside the tire "channel" about 12mm. *Or in other words, the rim comes up on the tire about 12mm.

If we use the 572mm rim as accurate, then we would take;

572mm - 24 (12 X 2) = 548mm for the inside tire diameter.

Does anyone have any input on the wheels or tires?

For sure someone at Fokker in 1918, screwed up on the wheel drawing. *>

Best,
Dave W.

Hi dave,

The white clenchers and custom wheels that I'm using are very close to those sizes and they look like they should. So I would guess your conclusion is correct.

Rick I

Dave, do you have a cross section drawing of the rim?

Because if you do I can run that into Rhino and have it calculate the volume of the tire based on the drawings...

[Dave_Watts]

Hi Rick,

It's funny sometimes how you can't see something until you draw it out or put it down on paper, so to speak. *Well, when I reread my posting, I figured out what was going on, and it seems so obvious, I feel stupid. *:-[

The Fokker drawing I referred to comes from Vienna. *It is from the group of drawings that were discovered there in just the last couple of years. *These drawings are not widely distributed, and some are keeping them close to their vest. *> * The limited amount of drawings I was able to obtain copies of were almost illegible therefore forcing me to make "new copies" of them. * *And when I say illegible, I mean it, (although I am suspicious that when copies were made for me, they were deliberately degraded). *:-/

I can see now with hindsight, that the measurement that I quoted as 546mm must actually be 516mm, and if I only would have seen the forest for the trees, I would have remembered how Germans makes their arabic numeral "1"s like inverted "V"s, in many ways mimicking a numeral "4", and this was my downfall. *After retrospect, I feel this is my mistake, (forgive me for saying a German made a mistake). *:-[

The good thing is, the mistake has been caught! *

Hey Rick, you must have a more difficult task, as Pfalz must have had wheels made for them with the Pfalz logos on the hubs. *Keep at it! *:P

Best,
Dave W.

P.S. I hope I didn't drive you crazy with those damned smiley faces, but they are addictive. * *

[Dave_Watts]

Hi Grey,

Forgive me for asking, but what exactly would I gain from knowing the "volume" of the tire? ???

I do have the drawing of the cross section of the rim.

Best,
Dave W.

[Dave_Watts]

Hi all,

So, in conclusion, to answer my own question, the tire size for a Fokker D.VII, as specified by Fokker, is;

Total outer diameter - 760mm
Total interior diameter - 548mm

Best,
Dave W.

[QUOTE]

Nah quite simple actually. The logo is just a photo etched
disk inserted into the recessed end the hubcap/wheel retainer.
We have the Caps, Axel, and Wheels finished and Tires (here in my computer room closet) obtained.

PS. - I like the smileys too

[Dave_Watts]

Hey Rick,

Glad to hear you have your tires/wheels out of the way. I originally was going to use Universal smooth tread "30 X 5" tires and wheels. I bought four tires and tubes, and found original wheels that I had rebuilt. The problem with these tires are the sidewalls are a little too tall. My solution was to make extra large diameter wheel spat covers so as to cover part of the tire, and give the proper illusion of the short side wall original tires. :

If you are a nutball freak like me you may want to go with "original" size 760 X 100, (interior size 548mm) just recently made by Mikael Carlson in Sweden. He has them for sale. I just received my shipment of six tires, and they look great. He had them made by Continental tire company of Sweden, and he can provide airworthy certificates for them as well.

There are a number of us getting together to get the wheels made in quantity. Langdon Badger, Udo Jorges, possibly Fred Murrin, myself and some others are joining up in the effort. As a matter of fact, I think I'll do a posting on the tires being available for others to pick up on.

Did you pick up that Pfalz D.XII rigging data plaque from Jon Aldrich? I offered him $475, but he wanted $550. Since I'm not building a D.XII, I couldn't justify it, but you should have it! 8)

Best wishes,
Dave W.

Dave Watts,

I misread your posting and assumed it would help to have a virtual model of the rim/wheel assembly.

Hi all,

I have my friend Tony, he does know everythings. Ask him a question about this wheel correct size if he acknowedge.


Contact him ICQ #39741378

Karter