tires/tubes leaking green liquid?

[McDuff]

Unless someone actually "filled" your tubes with Slime, I don't think there should be that much of a difference in the "feel" of them. The proper way with Slime is enough to "coat" the walls of the tube, not add an inch thickness of it.

The fact that some is leaking just means that there is enough pressure inside to expel some thru the hole, but unless the hole is too big, it "technically" is still sealed. My brother has atv's on his land and there are green dots all over the tires when they are parked, but they still hold air fine.

[paramoto]

Sorry, I just saw this. Kix or shox tires require no maintenance. My last pair lasted 3 years, many, many trips and absolutely zero maintenance. I switched many years ago after a flat tire during a trip and have never looed back.

Ah, remember the dme telling me they did something to make the tires less likely to puncture. It must be the slime. According to this thread it makes them heavier than solid tires. Now I know why it felt hard to push. I don't need that I'm a weak quad. what I really need are the power assist wheels. I use the chair only very rarely my powerchair makes me more independent.

paramoto are those the kik mako youre referring to? IsMaisin if the chair were to sit a lot would that affect the marathon tires i.e. would I have to check the tire pressure often? I need the easiest to get around in but not high maintenance.

[IsMaisin]

...members said you had to be careful about under/over inflating them.

I'd rather have to only check the pressure when I'm going to actually use the chair.

Sorry I didn't notice these concerns earlier.

The pressure issue is complex. Going to Sheldon Brown's advice:

Pressure Recommendations
Most tires have a "maximum" pressure, or a recommended pressure range marked on the side of the tire. These pressure ratings are established by the tire manufacturers after consultation with the legal and marketing departments.

The lawyers want the number kept conservatively low, in case the tire gets mounted on a defective or otherwise loose fitting rim. They commonly shoot for half of the real blow-off pressure.

The marketing department wants the number high, because many tire purchasers make the (unreliable) assumption that the higher the pressure rating, the better the quality of the tire.

Newbies often take these arbitrary ratings as if they had some scientific basis. While you'll rarely get in trouble with this rote approach, you will usually not be getting the best possible performance.

Savvy cyclists experiment with different pressures, and often even vary the pressure for different surface conditions.

Optimal pressure for any given tire will depend on the load it is being asked to support. Thus, a heavier rider needs a higher pressure than a lighter rider, for identical tires.


Trikes and two-wheel trailers (ed - and Wheelchairs) are very different from bikes, because they don't lean in corners. Most tire wear comes from cornering forces. On a bike, these forces act on different parts of the tread, according to how far one leans into various corners at various speeds.

With a trailer or trike, all of the wear is concentrated on the middle of the tread. If you overinflate the tires, you'll be riding on only the very center of the tread, and it will wear rapidly.

In addition, wheel alignment is never going to be perfect. As a result, the paired tires will always "scrub" a bit. If the tires are rock-hard, this will cause rapid wear. If the tires are softer, they can flex slightly sideways to accommodate the scrub, without wearing the tread off.

Tire width and pressure are inextricably linked. It is a serious mistake to consider one independently of the other. Generally, wider tires call for lower pressures, narrower tires call for higher pressures.

Consider, for example, a tire one inch across, at a pressure of 100 PSI (pounds per square inch). Air is pushing down against the bottom half of the tyre cross-section with a force of 100 pounds per inch of length. Each sidewall of the tire bears half that load, and so each inch of length of tire sidewall will be under a tension of 50 pounds. Now let's consider a tire twice as wide, two inches across, at the same 100 PSI. Each inch of sidewall will be under a tension of 100 pounds. So, a wider a tire would ride harder, and need stronger fabric, if inflated to the same pressure,

The part of the tire that is actually touching the ground at any moment is called the "contact patch." Generally, the area of the contact patch will be directly proportional to the weight load on the tire, and inversely proportional to the inflation pressure. For instance, if the rear tire of a bike is supporting a load of 100 lbs, and the tire is inflated to 100 PSI (pounds per square inch) the contact area of the tire will be roughly one square inch. If the pressure is reduced to 50 PSI, the tire will squish out until the contact patch has become 2 square inches (or until the rim bottoms out against the tire.)

A common debate among cyclists centers on the issue of whether a wider tire has more or less rolling resistance at the same pressure. The constant pressure is proposed because it appears more scientific to eliminate this as a variable, but this is not realistic in practice. The short answer to this question is that, yes, a wider tire of similar construction will have lower rolling resistance than a narrower one at the same pressure. This fact is, however, of no practical value. If you are comparing two tires of similar construction, with the same load, and the same pressure, either the wider tire is overinflated, or the narrower tire is underinflated!

A tire is supposed to deflect a bit under load. This deflection the whole purpose of pneumatic tires. When you sit on your bike, your tires should visibly bulge out at least a bit under your weight. If they don't, they're overinflated.

Underinflation
• An underinflated tire will have more rolling resistance.
• An underinflated tire will be prone to pinch flats.
• An underinflated tire will tend to wallow and may even come off the rim • during cornering. This is a particular problem with wide tires on narrow rims.

Correct Inflation
• A correctly inflated tire will have negligible rolling resistance.
• A correctly inflated tire will not get pinch flats in normal use.
• A correctly inflated tire will absorb minor surface irregularities, improving rider comfort.
• A correctly inflated tire will absorb surface irregularities without bouncing and losing traction.

Overinflation
• An overinflated tire will have slightly less rolling resistance if the surface is very smooth.
• An overinflated tire is more prone to damage from sharp rocks and similar road hazards.
• An overinflated tire will give a harsh ride on anything but the smoothest pavement.
• An overinflated tire can bounce on surface roughnesses. This can cause dangerous interruptions in traction.

Airless Tires

Of all the inventions that came out of the bicycle industry, probably none is as important and useful as Dr. Dunlop's pneumatic tire.

Airless tires 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 tire uses all of the air in the whole tube as a shock absorber, while foam-type "airless" tires/tubes only use the air in the immediate area of impact.

Pneumatic tires require pumping up from time to time, and can go flat, but their advantages overwhelm these difficulties.

My advice is that if, during non-use periods, your tires go totally flat, you would be doing the right thing to take the pressure off the rims by taking the wheels off the chair, hanging the chair on a hook, or storing the chair on its side.

Certainly, checking the pressure before using after many months of no use is a very important thing. But you shouldn't have to do anything during storage.

I had a pair of tires hold air (with some pressure loss) over an entire year of no use while I was deployed with the Army. My experience is that if the tube is damaged during instillation or faulty, you will notice in less than a week that there is something wrong.

Finally, remember that in a chair, having (very close to) the SAME pressure in both tires is important. If one tire is different, the chair will pull to one side.

[rlmtrhmiles]

IMO, the pressure on these tires/tubes which came with the chair less that 6 months ago, is trash. They are Schwalbe marathon. On top of that oly rode around on indoor on hardwood. Maybe at grocery store 3-4X I understand all everyone saying here. Simply saying whatever tubes installed with tires when bought chair are garbage. This not a used chair. I have an old Quickie as 2nd chair with A/T tires on it and those NEVER LEAK. Only time need air in those is when putting new tires on it.

[wheeliecoach]

IMO, the pressure on these tires/tubes which came with the chair less that 6 months ago, is trash. They are Schwalbe marathon. On top of that oly rode around on indoor on hardwood. Maybe at grocery store 3-4X I understand all everyone saying here. Simply saying whatever tubes installed with tires when bought chair are garbage. This not a used chair. I have an old Quickie as 2nd chair with A/T tires on it and those NEVER LEAK. Only time need air in those is when putting new tires on it.

In my opinion...I NEVER had issues with my tubes and tires and the PSI on them. I have to put air in them from time to time...but that is to be expected. I have always had max pressure and the only time I had an issue is when my rim tape was crap. I also have never seen a tire that NEVER needed air from time to time unless they were solids. That I call BS on. I love my Schwalbes and have not had the issues I used to have prior to using them.

[Oddity]

Do you think camber causes "lean in" type forces on wheelchair tires?

Sorry I didn't notice these concerns earlier.

The pressure issue is complex. Going to Sheldon Brown's advice:



My advice is that if, during non-use periods, your tires go totally flat, you would be doing the right thing to take the pressure off the rims by taking the wheels off the chair, hanging the chair on a hook, or storing the chair on its side.

Certainly, checking the pressure before using after many months of no use is a very important thing. But you shouldn't have to do anything during storage.

I had a pair of tires hold air (with some pressure loss) over an entire year of no use while I was deployed with the Army. My experience is that if the tube is damaged during instillation or faulty, you will notice in less than a week that there is something wrong.

Finally, remember that in a chair, having (very close to) the SAME pressure in both tires is important. If one tire is different, the chair will pull to one side.

[jschism]

I also have never seen a tire that NEVER needed air from time to time unless they were solids. That I call BS on.

Definitely B.S. That guys(rlmtrhmiles) advice often is BS.

[IsMaisin]

Do you think camber causes "lean in" type forces on wheelchair tires?

Good point. This is my opinion, not backed by an expert I can reference, but if you have a certain camber that you stay at for the life of the tire, you will get your wear on that small point of contact only.

I really don't think that "lean in" forces are applicable to most wheelchair users, though they may well affect athletes in sport chairs or thrill-seakers who try to run long downhills at 20+mph. We "normal" users put so little side pressure on our tires that the effect over a tire's lifetime is minimal.

Interestingly, the lower your pressure (which works best with wider tires) the larger your contact spot. The larger your contact spot, the more miles you can get from a tire before showing wear. This is mitigated by thicker tires like the Schwalbe Marathons. The only users I have ever heard of wearing out Marathons (not just wearing the tread out) were bikers on multi-contenent tours. One rider told his story on Crazy guy on a Bike and mentioned that he had done 20K miles on a trike with marathons and had not yet worn them out. If I remember correctly, he biked Alaska to Tierra del Fuego, then Rotterdam to Beijing all on one set of tires - without a flat.

Now, one huge benefit of camber is that, when your tires show wear, you can dismount the tire and reverse it on the rim to have a brand new contact patch. You can have double the lifespan of your tire by doing this and people with 0˚ camber do not have that option.

With my Icon and its easily adjusted camber, I can roll on 0˚, 2˚, 4˚, and 6˚ of camber and reverse the tire for all settings except 0˚. That gives me a hypothetical seven times the normal lifespan of the tire.

Of course, I, and I assume most people, tend to stick with the camber we like best, but we can still double the lifespan by reversing the tire.

[IsMaisin]

In my opinion...I NEVER had issues with my tubes and tires and the PSI on them. I have to put air in them from time to time...but that is to be expected. I have always had max pressure and the only time I had an issue is when my rim tape was crap. I also have never seen a tire that NEVER needed air from time to time unless they were solids. That I call BS on. I love my Schwalbes and have not had the issues I used to have prior to using them.

I have had problems occasionally, but every single time it was my fault for installing the tire incorrectly and the problem surfaced immediately. When first learning to change tires, I stressed the stems or pinched the tube during instillation. Like I said - my fault, problem showed up right away.

Marathons were my commuting tire on my trike. All weather, one tire constantly in the gutter with all the trash, broken glass, construction debris, ice, rain, gravel - and I still haven't worn out my first set with over 10K miles on them.

They aren't the fastest on a trike (I love Schwalbe Kojak's for speed) and they are heavy, but I'd put a Marathon Plus against a non-pneumatic solid any day for reliability, and the smoother ride and reduction of stress on the chair from jolts is well worth the hypothetical tradeoff of a solid tire's "impossible" to get a flat and the Marathon Plus's "almost impossible".