3.00 or 3.50 tire?

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Model T Ford Forum: Forum 2017: 3.00 or 3.50 tire?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Friday, August 11, 2017 - 12:23 pm:

Brought home a flat tire from the KS T barn to go on what was thought to be a 17 Roadster, but is looking more and more like a 20.
The tire is smooth tread US Rubber military tire that is shot and needs to be replaced. I'll get two and do one here and one when I get back to KS.

The current clincher tire is a 30 x 3.00. If I find a good deal or a pair of nice used tires, can I put a 3.50 on the current rim?

Looks like the slick tires were up to 16, so some sort of tread like the rears would be a nice upgrade. Sticker shock over the price of the tires, so don't want to make a sizing mistake.

I'll hang up and listen.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Friday, August 11, 2017 - 12:29 pm:



Won't interchange, the tire must match the rim.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Friday, August 11, 2017 - 12:50 pm:

Can you? Well, I've seen it done, but I wouldn't want to do it myself. When we got my wife's Touring, it had 30x3-1/2 all the way around, even on the 24" rims up front. Archimedes said you give him a lever and he'd move the world. So I guess with a big enough tire iron they managed to do it. It has 30 x 3 now.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eckensviller - Thunder Bay, ON on Friday, August 11, 2017 - 02:43 pm:

Robert, just to make some further sense out of it (maybe you know this, maybe you don't), clincher tires are measured by outside diameter then width. Because they have a round cross section, you can assume that the width will also be equal to the amount of tire above and below the rim. So, doing the math, a 30 x 3.00 would be 30" tire diameter, minus 3.00" above the rim and 3.00" below, making it fit a 24" rim. The 30 x 3.50 is 30" of tire minus 3.50" above and below, leaving 23" left in the middle for the rim.

The only trouble is they then made "oversize" tires to fit the rim for whatever size is moulded in the sidewall though the tire itself will be larger around the outside. Tire sizing is confusing, at best.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Friday, August 11, 2017 - 05:27 pm:

OK. 3.00 it is for me on the front two wheels. Now to find a good value . . . someone on eBay has free shipping.

TO THE DARK WEB!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Friday, August 11, 2017 - 07:30 pm:

A slight drift, related to tire sizing.
A 30 X 3 1/2 "oversize" clincher tire is actually a deliberately mislabeled 31 X 4 clincher tire. Blame marketing. Nothing new here. Marketing did that back in the early '20s to appeal to the huge number of model T owners and increase sales on the slightly more expensive and more profitable 31X4. People are funny things. They wouldn't buy the 31X4 because it was the wrong size, and they were afraid of fitting related failures. However, a 30 X 3 1/2 "oversize" was perceived as being "better", not "wrong". Even though it was exactly the same tire except for the sizing designation.

Just be sure by rim size which size you need (probably 30X3), and go for it.


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