Measurement of Wheels

[talbot-2]

I have read various online ads and articles, including our forum threads, that list early motorcycle wheel sizes as 22", 23", etc. In an early Indian sales catalog, Indian lists the wheel size as 28" and the tire size as 2 1/4". However, it appears that the current measurement for the same 28" wheel would be 22" or 23". Is there a standard method of measuring a wheel's size?

[Tommo]

I am currently recovering from a stroke and am having a few difficulties so please bear with me.
You'll find the answer to your question in the Indian Scout section under the heading " Early Scout rim dimensions"

[c.o.]

Tommo! It's good to hear that you are on the recovering end! Your absence has had me wondering. I hope you are 100% soon!

Here's the link for the rim dimensions... http://www.antiquemotorcycle.org/bbo...rim-dimensions

[silentgreyfello]

Thanks for the pics, Tommo. Get well soon!

[talbot-2]

I am currently recovering from a stroke and am having a few difficulties so please bear with me.
You'll find the answer to your question in the Indian Scout section under the heading " Early Scout rim dimensions"

Thanks for the link to the thread with some info about tire sizes. I noticed in one of the Tire Charts in the thread a reference to both Universal and Coker tires that were sold as "28 X 2 1/2-2". What's size is that? And how does the "28 X 2 1/2-2" tire compare in size with the current Coker tire size of "28 X 2 1/2"?

[rwm]

it's good to hear from you tommo

[Tommo]

Thanks for the concerns guys.

talbot-2
I suspect they are what is known as a "Group Sizing"
If you take 26 x 2 1/2 for example most of the tyres you buy will have "26 x 2 1/2" and following that in brackets "( to suit 2 1/4 rim)"
To understand this the following maths is probably best
2 1/2 plus 2 1/2 = 5 inches subtracted from 26 gives a rim dia of 21 inches
2 1/4 plus 2 1/4 = 4 1/2 inches subtracted from 26 gives a rim dia of 21 1/2 inches
So you see there is only 1/2 an inch difference so the tyre makers make the group sizing tyre slightly larger in dia so it is a bit loose on a 21 inch rim and just a bit tight on the 21 1/2 inch rim. Works just fine.
I suspect that this is what Coker and Universal are doing here but as the difference in rim dia is 1 inch I would get a bit uneasy about the possibility of them coming off the smaller dia rim. 28 x 2 1/2 = 23 inch rim 28 x 2 = 24 inch rim
Maybe this is where some of todays tyres get a poor reputation from.
I hope all this makes sense as this is where my recent stroke has caused the most trouble.

[c.o.]

It made absolute sense Tommo. Now I know what tire size I need for my Indian rims!!

[talbot-2]

I have read various online ads and articles, including our forum threads, that list early motorcycle wheel sizes as 22", 23", etc. In an early Indian sales catalog, Indian lists the wheel size as 28" and the tire size as 2 1/4". However, it appears that the current measurement for the same 28" wheel would be 22" or 23". Is there a standard method of measuring a wheel's size?

Okay............Back to my original question. "Is there a standard method of measuring a wheel's size?" The diameter of the wheel is measured from "where" to "where"? I have been told that a wheel is measured from the inside of the rim where the spokes are inserted to the other side where the spokes are inserted. I have also been told that a wheel is measured from the outside of the rim to the other outside. I'm just seeking a consensus for measuring pre-1915 wheels. Is there a standard method?

Picture this......you find a wheel that may be the one you're looking for....but is it a 22" rim, a 23" rim, or a 24" rim?

[Tommo]

I rang Brian Black who manufactures these sort of rims here in NZ.
He comfirmed my thoughts and the measurements shown on the attached document are the industries standard.
You measure from the bottom of the tyre bead.