Can a 30 X 3 Tire Be Used on a 30 X 3 1/2 Rim?

[Hudson29]

As mentioned in the Samson Tire thread, the spare hiding under the very nice tire cover was a Samson. It is a straight 30 X 3 1/2 size, not the EX size. I have in mind getting the car on the road and out to a show in a neighboring town a distance of 30 or so miles away. The '23 has a good spare & I thought it would work well on the '14, both have demountable rims so why not?

Whall, it turns out that not all these tires are the same size. I could not even JAM the '23 spare into the '14 carrier, its too wide & tall! Not only that, that wonderful tire cover wouldn't fit either! I tried one of the new Ward's Riversides on the ground and while they could just be JAMMED into the carrier, they were still too big for the cover. OK, I'll go without a spare this trip and rely on mobile coverage and the AAA card to get me out of any jam.

Beyond the immediate need, what can I do to get useable spare that will fit both the carrier & the cover? My feverish brain wondered if a 30 X 3 tire is enough smaller to fit both the carrier & the cover?

Paul

[Hudson29]

That last picture shows the Riverside JAMMED into the carrier.

Paul

[Norman Kling]

No. The 30" refers to the outer diameter, but the 3" or 3 1/2" refers to the rim. one is half inch wider than the other and should use the correct rims for each size.
Norm

[Chris Instness]

It cannot. A 30x3 uses a 24 inch diameter rim and a 30x 3.5 uses a 23 inch diameter rim.

[Allan]

If your spare tyre brackets are brass reproductions, you could open them up a little to take a fatter tyre. Cast iron originals may not like being "bent"

Early cars carried spare tyres, but they were not mounted on rims, so they would easily fit into your bracket.

Allan from down under.

[Steve Jelf]

I don't think I've ever heard of demountable rims that take 30 x 3 tires. If you have 30 x 3½ rims all around, the usual situation with demountable rims, a 30 x 3 tire will not fit. Period. I'm not aware of any law that requires spare tires to be covered. I covered a lot of ground carrying uncovered spares. The normal tires before 1919 are 30 x 3 in front and 30x 3½ in back. Carrying a spare front tire and a spare rear tire was never a big problem for me. I never thought of trying to cover them.

One front spare, one rear spare.

[Humblej]

Not only are tire outside diameters different from one manufacturer to another, 30x3.5 rims are different from one manufacturer to another. Add to the equation that you have aftermarket wire wheels on one of the cars, all bets are off that your rims are interchangeable between your two model T's. In the picture of the two rims side to side, I can see the lugs are different. Before you make that carrier fit the other spare rim and tire make sure it will fit your wheels first.

Early tire sizes are confusing. The "30" in 30x3.5 refers to the outside diameter of the tire, and the "3.5" refers to the dimension from the outside of the tire (tread) to the inside of the tire (bead). Doing the math, 30" - 7" = 23", and 30" - 6" = 24". So a 30x3.5 tire needs a 23" rim and a 30x3 tire needs a 24" rim. Today, most tire manufacturers ignore the actual outside diameter of the tire and make them whatever they want while maintaining the proper inside diameter to fit a given rim size. As to the width of the tires there are no standards for that size, today, or back in the day.

[speedytinc]

Ok, I'll stir this pot & duck..
Yes, you can run a 30 x3 tire on 30x3.5" rims. SEEN IT!

The story:
A group of T's were on tour in Big Bear Ca. We noticed one member had a flat. (15 with demountables)
He carried no spare, but had a new tube.
The tire was removed from the jacked up wheel, new tube installed.
We noticed the tire slipped on with a lot of room on the opposite bead.(big gap)
Surprise, the tire was a 30x3. The owners response was "15's are supposed to run 30x3's in front right?"
We got the tire to seat in the beads by rotating the tire & lowering the tire to the ground several times to force the bead in all the way around.
The tire did seat with the opposite normal fight.
Just when you think you seen it all!

We did what had to be done to get the T back on the road. & off we drove.

But, I definitely dont recommend this.

[Wayne Sheldon]

The "topic" question; about whether a 30X 3 tire can be used on a 30 X 3 1/2 rim?
Like John K, I too have seen it.
A long time ago, this was discussed extensively at the model T club meetings. Several members had read about it being done in old stories and books. A few made a minor effort to try it and doubted it could be done. A few people believed it could be done.
Not too long after that, our T club had a strange tour, quite a number of miles on beautiful mountain roads up to a wonderful park and picnic grounds with incredible views. What was strange about the tour was the number of breakdowns. Most of our cars were well restored and maintained, and we rarely had more than a couple minor problems on our tours. This tour had almost everybody breaking down with some minor thing as well as several odd major breakdowns that were overcome to complete the tour. We seldom ever (except on the 200 mile endurance runs) had a trouble trailer following.
Along with plugged fuel lines, major non-planetary gear transmission failures, timer failures, and several other system problems, were a bizarre number of flat tires. So many flat tires that nearly all the spare tires and tubes among all the tour cars had been used long before we reached the picnic grounds! Several spare tires or tubes had been loaned to other cars that had already used their own spares. Nothing like this had ever happened before.
So with about ten miles yet to go to the picnic grounds, another flat tire, a blowout, and the only spare tire left on the tour was a 30 X 3 front for a brass era T. The 30 X 3 was borrowed, and three determined helpers remained with the disabled car and driver to get that oversize rim tire mounted on the later rim. With enough helpers already, I chose to remain with the rest of the tour. About fifteen minutes after most of the rest of the group parked at the picnic grounds? In came the T with the 30 X 3 tire on its 30 X 3 1/2 rim and a couple of the helpers. They told us that a couple more cars at the back end of the tour had mechanical failures, but were attempting to patch them and limp on in. One was the 1925 Chevrolet, with a broken shift mechanism in the transmission, the other a T with an auxiliary transmission that the cast iron shift tower had broken off on a downshift going up a hill.
The T with the broken auxiliary transmission made it to the picnic grounds by the young son hanging onto the running board and in the door of the open front brass T, holding the gear in place with a screw driver as the car was driven the last several miles. At the picnic grounds, the broken shift tower was bailing wired back onto the transmission (took some creative effort by Ed Archer!) and then later driven home.

I told you. It was a strange tour.

The capper? At the picnic, discussion revealed that only two cars had not broken down in any way. Standing around chatting after eating, one of the fellows boasted "and I didn't have a bit of trouble!" As if on cue, fifteen feet away, a valve stem blew off of his rear tire! There was one more inner tube left.
I kept my mouth shut.

That tour was downright bizarre! But I got to see a 30 X 3 tire mounted onto a 30 X 3 1/2 inch rim.

[Allan]

When fighting the shrinkage in new-old-stock 30 x 3.5" tyres to get then stretched far enough to fit, I can well imagine a 30 x 3" tyre being fitted to a 23" rim. It should be a piece of cake. But there is no way a 30 x 3.5" tyre could be fitted to a 24" rim on a front wheel.

Allan from down under.

[Hudson29]

Thanks for all the replies about this situation. I have two concerns that caused me to think about doing this. First, I wanted to use the spare tire carrier that is on this car. It is not a reproduction but like everything else on the car is original. This car was built in the 1960s by a long time T mechanic who used original accessories rather than reproductions. I'm not above bending that brass top mount to get a 1/2" more clearance to fit a modern Riverside tire. How would it be bent without marring it?

The other consideration is the desire to use that excellent tire cover. It fits the Samson like a glove but will not fit the Riverside. This car is garaged and I do not need a cover. I want this cover because it is very nice and perfect for the graphics which lend the car a sense of place. I am Model T alone up here and all my tours are solo. I do take my cars to other events of a historical nature and that local connection would be appreciated.

While the Riverside was off the wheel, I slid the spare off the '23 onto the Hayes wire wheel on the '14 with no hoo-haw at all. Yes it filts and would certainly be useable.

From what I can gather from the opinions here, mounting the 3" tire on the 3 1/2" rim might work but it would be an emergency bodge rather than a workable long term solution. Too bad, I really liked that cover.

Here is a pic of the Commander off the '23 mounted on the '14 wheel.

Paul

[Steve Jelf]

There's that phrase again. I don't doubt there are aftermarket accessories from the Model T era on your car. Is the car "original". No. That phrase implies that the vehicle is much as it was when it left the factory. 26-27 wheels are from the Model T era, but on a 1914 they are not original. You can call them attractive. You can call them convenient. You can call them swell, and any number of other adjectives. But on a 1914 they are not original.

[Hudson29]

You are being too literal. The spare mounts are what we were discussing.

Paul

[DanTreace]

Thanks for all the replies about this situation. I have two concerns that caused me to think about doing this. First, I wanted to use the spare tire carrier that is on this car. It is not a reproduction but like everything else on the car is original. This car was built in the 1960s by a long time T mechanic who used original accessories rather than reproductions. I'm not above bending that brass top mount to get a 1/2" more clearance to fit a modern Riverside tire. How would it be bent without marring it?

Paul

With care the brass casting could be opened up some using heat to just slight dull red color. Too much heat can melt.

Those brackets as Allan mentioned are made to carry a deflated tire casing only, so the tire can compress into the brackets and held with leather straps.

Early tires are more true 30x3 1/2, any modern ones are actually 31x4, the so-called X-size. They fit 30x 3 1/2 rims but are larger width and height, so your original cover would be hard to use.

[Wayne Sheldon]

Something I don't know. It has been a couple decades since I bought new clincher tires. But several discussions about new clinchers around eight or ten years ago, a few comments were made about one particular available 30 X 3 1/2 tire being considerably smaller than all the rest. Unfortunately I do not know which one that was, or if they are still being made. Even if they are not being made anymore, if someone knows what the tire was that I heard about? A good used one should be available without too much trouble.

[Hudson29]

Something I don't know. It has been a couple decades since I bought new clincher tires. But several discussions about new clinchers around eight or ten years ago, a few comments were made about one particular available 30 X 3 1/2 tire being considerably smaller than all the rest. Unfortunately I do not know which one that was, or if they are still being made. Even if they are not being made anymore, if someone knows what the tire was that I heard about? A good used one should be available without too much trouble.

That might be a good solution to the problem. Does anyone know of such a smaller 30 X 3 1 1/2 tire?

I'll wait a bit before doing anything about this but should nothing positive develop, I'll see about heating that top bracket. Would a propane torch work for this?

Paul

[Wayne Sheldon]

A propane torch may not be quite hot enough. But the flip side is that it likely cannot be too hot. Several people I have known did use propane torches for annealing brass. I have always used oxy-acetylene.
Bending cast brass is tricky. Too cold or not annealed, and it may quickly snap into two pieces. Too hot and it may quickly snap into two pieces.
Ideally, it should be heated up to that "changes color slightly" point, then allowed to cool only slightly (I wish I knew the ideal temperatures, but when I learned to do this, our modern "laser" thermometers were only a dream). Actual ideal temperatures do vary with slightly different alloys, but a perfect range would be nice to know and share? It should cool only maybe a hundred degrees from that color change (reminder, that color change is very slight!) before attempting to bend it. Somewhere below about 200 degrees F the annealing might begin to fade away. Other times, the piece my be able to cool and remain at ambient for a few hours before the brass becomes brittle again. Different alloys make those differences, as well as brass has a funny way of changing when going through significant heat cycles. The more times it is heated, the less annealing will help with bending.

Be gentle! Brass goes from bending easily to broken in the blink of an eye! Welding brass is the same way. I have oxy-acetylene welded two sets of model T brass hubcaps as well as a few brass headlamp rims myself (couldn't afford enough nice ones). Very tricky to work with, but can be done.

You could try using two appropriately sized wooden wedges against each other to apply gentle pressure to spread the opening. Carefully done, the wedges applying slight pressure and heating the center area of brass away from the wedges, could allow the bracket to bend as soon as it is ready. If you need a more complicated reshaping? That may not be the best way to do it.

Good luck!