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Inflatable tires???

Old 02-20-2015, 05:29 AM
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abufletcher
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Default Inflatable tires???

The 30% Paulistinha comes with very nice inflatable rubber tires. There's a brass valve fitting on the inside and the kit includes a needle for it. Two problems though. FIRST, the provided needle doesn't fit any pump that I have or can find. So I reached for the trusty duct tape and that seems to work well enough. SECOND, the needle doesn't seem to actually insert into the valve on the tire (like a normal needle would insert snugly into a football). I can loosely slot it in but the tire doesn't inflate. It doesn't even look like the needle can be inserted any further.

So what gives? Has anyone used this type of tire before? I don't see a brand name anywhere. Am I just doing it wrong?
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Old 02-20-2015, 06:21 AM
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flyinwalenda
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I don't see any mention of it in the manual either. I can't tell if it uses a Schrader type valve like the ones from Dubro. Either way I would replace them with a set of treaded lightweight wheels from Dubro. They are a bit expensive but you will never have to worry about leaking tires. I've had the Dubro inflatables and never had good luck with them.
Old 02-20-2015, 06:24 AM
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Jennifer Curtis
 
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Maybe you need to turn the fitting with a screwdriver to
make it release the valve below it.

Jenny
Old 02-20-2015, 07:37 AM
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abufletcher
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Jenny, I was wondering the same thing since the valve has what looks like a slot in it. But I tried that and rotating it doesn't appear to do anything.

I was thinking of these inflatable tires as BETTER than that solid tires, but maybe that's not the case. (By the way, eventually, it might be cool to replace the tires with balloon-type bush tires.) These have a 4.5 inch diameter.

I found this thread on inflatable tires. Seems that others have had similar problems:

http://www.rcuniverse.com/forum/begi...what-pump.html

Last edited by abufletcher; 02-20-2015 at 07:50 AM.
Old 02-20-2015, 07:51 AM
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Jennifer Curtis
 
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I would expect one quarter or one half
turn to release a cam inside. The rubber
might be stuck closed. You might
need to lick the needle (or put a little
dish soap on it) to work it in the opening.

Jenny
Old 02-20-2015, 08:04 AM
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abufletcher
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Well, this sucks!
Old 02-20-2015, 04:28 PM
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Here is the answer to your inflating problem:
http://www.rcuniverse.com/forum/ques...ble-tires.html
Old 02-20-2015, 06:51 PM
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abufletcher
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Interesting. Thanks for the link. I've taken the wheels off the model for now and will play around with them a bit more. In the meantime, I've gone ahead and ordered a set of 6" solid tires which should look a bit better on this size model anyway:

http://www.kkhobby.com/SHOP/PT186.html

Last edited by abufletcher; 02-20-2015 at 07:43 PM.
Old 02-20-2015, 07:31 PM
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Prompted by Jesse's post in the other thread, I also disassembled the wheel and removed the valve. It's a bit different from the other one shown. In this case, there is a brass valve with a nut and washers on the inside. But it also has the pin-hole on the side. The inner part of the valve is covered with a short length of silicon tubing. I can see how this should, in principle, work (forced air expanding the silicon tube).

It's possible to insert a large T-pin about 1/2 inch into the valve, but the inflating needle only goes in about 1/8 inch. The needle sit in the hole very loosely and I would guess that too much air escapes round the needle. When i hold just the brass valve in my hand and pump air into it, I can feel the air coming out of the pin-hole. When I put the silicon tubing over the valve, it's harder to tell if air is coming through.

Nevertheless, no matter what I try I'm not getting any inflation whatsoever on the tire.
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Last edited by abufletcher; 02-20-2015 at 07:34 PM.
Old 02-21-2015, 04:58 AM
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Originally Posted by Jennifer Curtis
I would expect one quarter or one half
turn to release a cam inside. The rubber
might be stuck closed. You might
need to lick the needle (or put a little
dish soap on it) to work it in the opening.

Jenny
Now that I've taking it apart it's clear that the slot for a screwdriver is only there for installation purposes. At least that's the way it looks to me.
Old 02-21-2015, 05:11 AM
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abufletcher
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One more small test. I placed the end of the brass valve with the silicon tubing in place in water. The end with the needle was out of the water. When I pumped air, no bubbles come out so no air is going into the tire. All the air is redirected back out; you can hear it. The problem is that the needle doesn't fit snugly into the brass valve the way a needle would fit into a ball.
Old 02-21-2015, 05:15 AM
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Not sure what you are using for a pump but I had to use a compressor to fill the Dubro tires after a while. When the tires were new the hand pump worked good. Either way you did the right thing going to a good solid tire. As I said before these inflatables are too much trouble for any perceived benefit .
Old 02-24-2015, 05:35 AM
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abufletcher
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The wheels I ordered arrived today and the 5" wheels fit fine. The 6" wheels have a hole too large for the axle so I would have to add a brass tube extension or a brass inset to the wheel. At any rate, I'm not thrilled about the quality of these wheels. They seem rock hard.

So this prompted me to take another look at the inflation problem. The basic problem is that no air was going into the tire. I believe there are two reasons for this: 1) The silicon tubing over the valve is perhaps too stiff as opposed to the thin rubber tubing found on a bicycle valve and 2) the needle supplied with the wheels doesn't fit snugly in the valve. Nothing I can do right now about the first problem (but I might try to find some thin surgical tubing). For the second problem I put some tape around the end of the needle.

This seemed to work. Immediately it became VERY hard to pump air and the tires slowly started to fill. Which leads me to another question: HOW HARD SHOULD INFLATABLE TIRES BE? Mine seems to be as inflated as I can get it now and it still seems pretty soft...definitely too soft for a model of this weight.

So it's Goldielock's time: These wheels are TOO hard; these wheels are TOO soft...

Last edited by abufletcher; 02-24-2015 at 06:04 AM.
Old 02-24-2015, 05:53 AM
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These work great on light and heavy planes:
http://shop.dubro.com/p/6-dia-treade...price_high_low
Old 02-24-2015, 06:16 AM
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Success! Sort of. I took your idea of using a compressor and duct taped the needle (with its bit of tape on the end) onto the compressor gun and that immediately filled the tire. If fact, you have to be very careful not to overfill. The tire is still quite springy. Very springy, in fact. And the diameter increased noticeably.
Old 02-24-2015, 06:17 AM
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Originally Posted by flyinwalenda
These work great on light and heavy planes:
http://shop.dubro.com/p/6-dia-treade...price_high_low
'

Is that the price for one or a set? I guess I was just over-eager to get a set NOW and so ordered an unknown brand from here in Japan.
Old 02-24-2015, 07:12 AM
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The inflatable wheels are now inflated. (But how air should they have?) The trick seems to have been to use a compressor. A sport-type hand pump just doesn't provide enough pressure to force air through the silicon tubing (which I have replaced with standard fuel tubing on both tires).

So this means I now have the inflated (but soft) 4 1/2" wheels and the rock hard 5" wheels, both of which fit on the gear. The larger 6" were, unfortunately, a complete waste of money.
Old 02-24-2015, 07:22 AM
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Originally Posted by flyinwalenda
These work great on light and heavy planes:
http://shop.dubro.com/p/6-dia-treade...price_high_low
How flexible are the DuBro tires?
Old 02-24-2015, 05:21 PM
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Originally Posted by abufletcher
How flexible are the DuBro tires?
They are low bounce (in my opinion). I have them on a 16lb plane and a 30lb plane and they work well. They are a good mix of firm and flex yet not rock hard plus they don't get flat spots from sitting like some tires do on heavy planes and they last a long time if flying from grass. On pavement I'm sure they would wear quicker.
They are somewhat expensive at $22.00 per wheel.but they are well worth it for not having to deal with the inflatables.
Old 02-24-2015, 10:07 PM
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Low bounce. That's definitely how I would describe the wheels I ordered. They bounce about as much as a baseball hardball on a wooden floor...or as much as any other hunk of plastic. No matter how much I squeeze them with my hands, I can't deform them in the slightest. Is there really any advantage of such rock-like tires?

For now, I'm going to use the inflatables and see how they perform and whether they lose air over time. If they don't work out, I'll order the DuBro wheels down the line.

Last edited by abufletcher; 02-24-2015 at 10:09 PM.
Old 02-25-2015, 04:07 AM
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I've seen some tires like that and I don't know what they would be good for . They usually come on cheaper arf's I see at the field and I'll recommend to the flier to get some softer tires, especially after they have a few rough ,bouncy landings !

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