Brass era tire sizing...

[Tom400CFI]

Why don't brass era car tires have a sizing system to specify the RIM DIAMETER??

33x3. <That is a tires size. The tire is 33" O.D. and 3" wide. It could fit on a 10" rim or it could fit a 30" rim...you don't know. I'm asking b/c we bought tires for out '10 Hupp. It had 33 x 3 tires on it. We couldn't find that size when getting new ones so we got 33 x 3-1/2. No where on either tire does it specify rim size. Went to put tires on today...they're 2" too small on the rim. Grrrr.

How do you get a tire that fits your rim, is the right width, and right OD?

Edited June 4, 2013 by Tom400CFI (see edit history)

[Tom400CFI]

Now I can't get this forum to post everything that I typed. I guess that I can't get anything to work right today.

Let's try again...

Why don't brass era car tires have a sizing system to specify the RIM DIAMETER??

33x3. <- That is a tires size. The tire is 33" O.D. and 3" wide. It could fit on a 10" rim or it could fit a 30" rim...you don't know. I'm asking b/c we bought tires for out '10 Hupp. It had 33 x 3 tires on it. We couldn't find that size when getting new ones so we got 33 x 3-1/2. No where on either tire does it specify rim size. Went to put tires on today...they're 2" too small on the rim. Grrrr.

How do you get a tire that fits your rim, is the right width, and right OD?

[Layden B]

Early tires were designated with a system as you have shown, that is a large number then an X then a small number. Your example would be pronounced "33 by 3". The large number is the OD of the tire and the small number is both the width and the height of the tire as tires were round in cross section in the earliest days. The rim dimension can be deduced by subtraction the tire size twice from the OD. Your example becomes 33, minus 3, minus 3, equals 27" rim size.

The 33 x 3-1/2 would be 33, minus 3-1/2, minus 3-1/2, equals 26" rim size.

If they are clincher tires you MAY be able to stretch them on if they are warm and pliable with a lot of talcum powder for lubricant, just maybe.

In the old days they had many sizes that are no longer available. You may have to go to a larger tire. A 34x3-1/2 would fit a 27" rim as would a 35x4. The larger size tires however may be too wide to fit your rim. I hope you are not in the situation that some owners find themselves, there is no tire available to fit their rims and they have to change the rims to get tires on the car!

There is also an issue with straight side tires and clincher tires.

Hope this helps.

[Tom400CFI]

Great reply. Thank you so much for the clarification!

[Seldenguy]

Tom, your '10 hupp should have 30X3 tires on it. At least my '11 has them and I believe they are original and the same as the '10. If your wheels are not 24", apparently someone has changed them sometime during its lifetime. I would measure the flat(bottom of the rim) to the flat(bottom of the rim) on the opposite side to get the wheel diameter in inches. Then as Layden suggests this gives the basic number to which you add the cross section in inches doubled. And that is the tire size needed. I also feel the correct tire size on the rim is an important safety factor. Good luck in your efforts. ---Bob

[Tom400CFI]

That is correct; the tires that I removed are 30x3. They were worn to the nylon. Wheels are stock/original. They are ~24", flat to flat. Just over 25", total OD.

[Layden B]

30x3 clincher tires are a common size as they were used on the front of Model T Fords until 1919.

Try the Model t parts suppliers

Wards Riverside Tire

Model T 30 x 3-1/2 Wards Riverside Tire, Black, original Wards tread, TIRE2WARD

and of course the tire manufacturers

[Tom400CFI]

Copy that. Thanks for the links.

What are "clincher" tires?

[Layden B]

Tires of today are called straight sides but in earlier times were named for their developer John Dunlop. They stay on the rim because the tire bead cannot expand due to wire strands imbedded in the rubber.

Another way to keep the tire on was used in the early day and it is called clincher. The tire does not have wire in it so it can be stretched over the side of the rim for mounting. The rim itself is hook shaped on the edges and the tire bead formed to match. When the tire is inflated the rim prevents the tire from stretching and coming off.

There were other methods as well very early on but they soon fell out of favor with the clincher continuing on cars into the 1920s.

[Seldenguy]

Tom, that is a great thread you started below under domestic makes & models on your Hupmobile. Looking good, --Bob

[KenHupp20]

Hi Tom, You might find this video interesting . I've not tried it myself.

Good luck , Ken

[Tom400CFI]

Thanks for the comments and video! That was a very interesting vid! Cool.

Tires of today are called straight sides but in earlier times were named for their developer John Dunlop. They stay on the rim because the tire bead cannot expand due to wire strands imbedded in the rubber.

Another way to keep the tire on was used in the early day and it is called clincher. The tire does not have wire in it so it can be stretched over the side of the rim for mounting. The rim itself is hook shaped on the edges and the tire bead formed to match. When the tire is inflated the rim prevents the tire from stretching and coming off.

There were other methods as well very early on but they soon fell out of favor with the clincher continuing on cars into the 1920s.

Thanks for the clear description! That was great. Thanks you. I sent the old tires back...new ones are on the way.

-Tom