Understanding antique tire sizes?

[Chase392]

Hey guys,

 

       I need some help understanding tire sizes on antique vehicles. Until I bought my speedster project the oldest vehicle I owned was made in 1968... I'm wanting to fit a tire that is approximately 35" in diameter and I have been offered a set of 24" rims. I've been looking at tires on Coker's website (I am unsure of where else to look) and I really don't understand the how vintage tires are sized.

 

Looking for something that is correct for a mid to late teens large car....

 

Thanks in advance.

[trimacar]

The formula is simple.  The first number is the outside diameter of the tire, the second number is the size of the tire in inches from the rim to the outside of the tire.  Thus, a 30 x 3.5 tire has an outside diameter of 30 inches, and a rim size of 30 - (2 x 3.5) = 23 inches

 

In your example, it's possibly running a 34 x 5 tire (34 - (2 x 5) = 24 inch rims).  

 

In the example of the Model T size tire (30 x 3.5), at one time they actually made one size up, a 31 x 4 (still 23 inch rim) to handle heavier loads on the same rim.

[1912Staver]

Good rims , and all of the associated hardware are much harder to find than tires.  24 " or 25 " rims were quite common on later teens cars . These are complicated rims, generally the detachable, demountable style with side rings, lock rings , fellow bands , fellow band rings { wedge rings} and all the rim bolts and clamps. And there are many different manufactures and styles, so if any pieces of the puzzle are missing it can be quite frustrating to find the correct component. Ideally a person finds a complete set but in reality this rarely happens. Also mid to late teens cars almost always used wood fellow wheels. They seem to be much harder to find than the slightly later steel fellow wheels of the early 20's onward.

  There is quite a bit of information in older editions of Dykes . I have a chart Firestone published in about 1960 when they got back into the antique car rim and tire business.

If I can find it I will scan it and provide a link. It gives a good picture of what tire fits on what size rim.

 

Greg in Canada

Scan0001.pdf

Edited December 12, 2016 by 1912Staver (see edit history)

[Chase392]

Thank you for the info guys,

 

    What about a tire that is listed as XXX-XX? For example a 600-16 tire?

 

[1912Staver]

600-16 would be a 6" wide tire on a 16" rim, a much more modern combination. Later 1940's - 1950's and possibly a light or 1 ton truck size.

I am curious what chassis your speedster is based on ?  It is often a good idea to stick to the tire diameter that was used OEM . Or even a little larger. Otherwise the speedster will end up under-geared and will possibly need an expensive, higher ratio ring and pinion to get the sort of road speed modern roads will allow. Most vehicles in the teens were generally used below 45 MPH or so.

 

Greg in Canada

Edited December 12, 2016 by 1912Staver (see edit history)

[Chase392]

6 minutes ago, 1912Staver said:

I am curious what chassis your speedster is based on ?  

 

The frame is from a White 1.5 ton truck.

 

But the engine is from a Seagrave fire truck.

 

I just started my build thread in the Speedster forum yesterday 

[1912Staver]

That changes things quite a bit. I assumed you were building a car based speedster. For a project using a fire truck engine you would be best to stick with the sort of wheels that they generally used when new. Early trucks almost always used Firestone 24 "  commercial series rim equipment.  Goodyear made something similar but they seem to be quite a bit rarer.  I will dig a bit more and post what Firestone material I have. Good rims are hard to come by , Early trucks were hard on wheels and rims. I have been piecing a set together for my 1 1/2 ton Packard for quite a few years.

 

Greg in Canada

[Chase392]

10 minutes ago, 1912Staver said:

That changes things quite a bit. I assumed you were building a car based speedster.

 

The frame does fit in regular parking space 

 

I actually trying to get away from fire truck sized parts.... I don't mean any disrespect to anybody building a fire-truck based speedster.... but the proportions are usually way off.

 

I don't think my engine is any larger physically or any heavier than a WW1 vintage aero engine.

 

 

[1912Staver]

In that case you would need to use something in the Packard twin six sort of size. You also mention a chain drive transaxle, it's going to be very difficult to use that with anything automotive sized. It does however make the gear ratio problem a lot more manageable. Large car chain drive rear axles ; Locomobile, Benz, Simplex, Etc.are very rare.

 

Greg in Canada

[Chase392]

My transaxle is from an American Lafrance front drive tractor,

 

My driven axle and front axle are stout pieces.... but I don't think either one is from a fire truck. I can carry the bare front axle around by myself, its a close (but not exact) match to the front axle in the Blitzen Benz in size and shape.

 

I'll be adding info on my axles to my build thread in the next day or so.

 

10 minutes ago, 1912Staver said:

 Large car chain drive rear axles ; Locomobile, Benz, Simplex, Etc.are very rare.

 

 

Yeah I get the feeling if I was setting on a handful of them I could retire at 33.....