As a child I had solid rubber inner tubes in my bike. They were a pain to get on but after I never had a flat again!
Now I've recently started biking again and have had two flats in two days, each resulting in a three-mile walk back home. I've been searching for solid rubber tubes for a few hours now, but have only found them at wal*mart, and they don't have the correct size? (700x38c)
Why have they disappeared? I thought they were a fantastic product . . .
You should not be getting multiple flat tires in such a short timespan. I commute on poorly-maintained roads in Atlanta, and have not had a flat tire in 4,000 miles.
In order of estimated likelihood, either:
If you've just started cycling again, I think it's exceedingly probable that you've simply neglected to inflate your tires to their recommended pressure. Standard road tires should be inflated to pressures of 100PSI and beyond. Mountain bike tires (which are awful for road use, but I digress...) require much less. It's easy to grossly underestimate how much to inflate a bike tire, and a standard hand pump will likely only get you to 30-60 PSI before you give up.
Take your bicycle to your nearest bike shop and have them examine the situation. Flat tires should not be a common occurrence.
Basically, they're harsh and hard on your wheels. A quick look at Sheldon Brown's site will tell you more:
Airless tyres have been obsolete for over a century, but crackpot "inventors" keep trying to bring them back. They are heavy, slow and give a harsh ride. They are also likely to cause wheel damage, due to their poor cushioning ability. A pneumatic tyre uses all of the air in the whole tube as a shock absorber, while foam-type "airless" tyres/tubes only use the air in the immediate area of impact.
Also, many shops will discourage airless tires. It's certainly possible they may get better given time, though, so it's worth keeping an eye on the situation.
To address the other part of your question, they're still available, but a specialty item. I found quite a few of them on Google Products, although finding them in 700x38 might be a challenge.
To answer the actual question, they are no longer sold in the US. In most locations, they aren't legal to sell. A bicycle tire uses the pressure from the inflation of the tube, (or in the case of tubeless tires, the tire itself is inflated), against the casing of the tire to lock the bead of the tire into the rim.
Without that pressure lock, the tires roll off the rim.
Since a solid tube or solid manufactured tire can't by definition inflate against the bead, they were both abnormally hard to install, and prone to rolling off the wheel in use. So they were considered unsafe, and are no longer sold anywhere that I am aware of.
Certainly, no reputable shop will sell them.
Carry a flat-fixing kit. You don't need much; patches, tire tools, something to inflate the tire again. Small, light frame-mounted pumps are readily available, and if you don't want to pump, CO2 inflators. You can even get hand-clean-up goo in handy little packs.
With a bit of practice you can be rolling in about the same time needed to change tires on your car.
As well, you can take preventive measures. Avoid super-light tubes. Keep your tires properly inflated. Keep an eye out for visible hazards like potholes and broken car-window glass.
I came across a solid tire. SERENITY
https://www.bikeradar.com/news/eurobike-2010-hutchinsons-puncture-proof-serenity-tube/
Airless tyres are available at least from Tannus but they're not solid tubes. They're solid tyres. A tube is something that fits inside a clincher or tubular tyre. I can't imagine how fitting a solid tube would be possible. There are several armors but they are not tubes, they are armors that fit between the air-filled inner tube and the tyre.
You shouldn't use airless tyres, however, as on nearly any kind of road they have excessive rolling resistance, which makes you so slow it takes the enjoyment away from cycling.
About the only case where extra puncture protection helps is areas that have ice on the roads during some parts of the year, and also at the same time have flawed decisionmakers that think cyclists should use the same paths that pedestrians use.
Pedestrians would fall all the time on ice, because ordinary shoes don't have studs, so therefore they distribute a form of sharp gravel made from crushed rock on these paths. This sharp gravel can have thin and long pieces as long as 14mm. The reason this happens is that they use 6mm sieve to filter away the largest crushed fragments, but a 5mm x 5mm x 14mm fragment would be small enough to fit through that sieve, as the sieve only restricts the two smallest dimensions of gravel pieces, and not the largest dimension of gravel pieces. Also, the crushed rock makes the gravel extremely sharp.
The combination of wet paths from melting snow and sharp gravel fragments that may be as long as 14mm mean that you have more than one puncture per 100km if you use ordinary tyres. The water acts as a lubricant between tyre rubber and the gravel pieces. In this case, I understand that someone might want to have extra puncture protection. However, also if riding in this environment you benefit from studded tyres. There are no studded airless tyres available, but you can buy a very thick tyre armor from Tannus. It fits inside the studded tyre and the inner tube but you do need to use much smaller inner tube because the armor is so thick. It can be used with any tyre, including a studded tyre.
The armor successfully prevents sharp gravel from puncturing your tyres. It also has a very high rolling resistance and is a real pain to fit between the tube and tyre (so you want to fit it once to a secondary wheelset and leave it there, not changing it every season). You want to use this armor only during the times the sharp gravel is on the roads. Once it has been collected away from the roads, you should swap to a summer wheelset that has low rolling resistance (=thin) tyres and no armor.
