What type of compound in this tire? No tube

[ebike11]

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hi guys
the tire on my friends bike was almost bald so he went to change the tire and upon removing it noticed there was no inner tube. The tire was filled with this hard spongy type compound. He had to cut the tire to get everything off. There was also no stem. I think the previous owner did something to the wheel. Any ideas?

 

[Warren]

I assume it is a urethane foam rubber. You can have it made to basically any density. This stuff has been around for decades. I was in a local bike shop the other day and noticed that Specialized was selling hybrids with this setup. Lousy shock absorption, poor traction, but no flats.

 

[Chalo]

The main drawback to foam tires and foam fillings is that they don't put the tire under elastic tension like a pneumatic liner does. So the wheel must carry all its load on just the area over the contact patch, which stresses the rim and de-tensions the spokes much more than an air-filled tire. It decreases the service life and reliability of the wheel by an order of magnitude.

I think the poor ride quality of foam tires would be an acceptable trade-off by itself, but coupled with the punishment it inflicts on the wheel, not so much.

 

[USAEBIKECO]

I tried tubeless tires on one of my ebikes and it ended in disaster.

 

[hypertoric_amplituhedron]

Those solid foam tubes are only good for post-industrial apocalypse riding, when you absolutely cannot have a flat tire.

I tried tubeless tires on one of my ebikes and it ended in disaster.

Oh, heavens no. Let me guess, the tire burped off the back wheel in a corner, and it dug into the ground, which sent you flying?

 

[1JohnFoster]

The main drawback to foam tires and foam fillings is that they don't put the tire under elastic tension like a pneumatic liner does. So the wheel must carry all its load on just the area over the contact patch, which stresses the rim and de-tensions the spokes much more than an air-filled tire. It decreases the service life and reliability of the wheel by an order of magnitude.

I think the poor ride quality of foam tires would be an acceptable trade-off by itself, but coupled with the punishment it inflicts on the wheel, not so much.

Chalo, what do you recommend for flat-proofing & run flat?

I've done a lot of miles with Mr Tuffy liners. At first they cut the tube because the end was sharp. Then I started sanding down the ends so they were not so sharp, they didn't cut after that. But still occasionally I get flats from long construction screws that happen to puncture past the edge of the tuffy.

I've long thought of having a run-flat rubber or foam core inside the tube, or under the tube. That way I could at least keep going and get to work and back without too much delay, and patch the tube later.

 

[MadRhino]

Unfortunately, to have a tire that is light weight and riding fine, you have to accept the risk of a flat. Adding a few ounces of slime is an acceptable weight compromise and does make a tire relatively flat safe.