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Thread: Figuring Out Wheelchair Tires and Introduction

  1. #1

    Figuring Out Wheelchair Tires and Introduction

    First, I'd like to introduce myself. My name is Ryan. I came across this forum searching the web for wheelchair tire help for my 10 year old daughter. She uses a Rifton Dynamic stander (https://www.rifton.com/products/stan...obile-standers) more or less all of her waking hours. We are in need of new tires and Rifton hasn't really been too helpful. I've attempted to figure out tire labeling but after doing way too much reading about ETRTO, bead seat diameter, etc, etc I think I'm more confused than before I started.

    The tires that came on the stander are a certain brand/size (solid polyurethane tires), but the replacement tires of the same specifications (same brand/specs/exact model numbers) simply will not go on the rim. I took them to a local bike shop and they broke (big pop) one of the tires trying to get them on with the appropriate tools. My father is an owner of an auto mechanic shop and we tried to stretch the remaining tire with an industrial come-along and then used the tool (http://enableyourlife.com/wheelchair...ation-tool.asp) to try to mount the remaining tire and it was not happening. We probably put several thousand pounds of pressure on the tire trying to get it to stretch. Much more than the tool would allow by itself. But it wasn't even close. If we did somehow manage to get it on the rim I think the rim would bend.

    The tire we took off the rim is significantly larger than the replacement tire of the same brand/model (numbers match). I hesitate to give the exact numbers on the tire on the forum as I don't want to influence the potential responses. We're pretty convinced that even though the numbers match that the tires we purchased are too small. I spoke to rifton technical support and they buy the rim/tire combination from a 3rd party and pass them along to the customer (something like $700 bucks for a replacement set). They indicated that this 3rd party heats the tires in some way, which makes sense as I see no other way they could mount/stretch the amount required to get on the rim. I own a Porter Cable heat gun and I tried heating the tires but it didn't really seem to do too much. I know that stretching of solid tires is required, but I just really don't think these tires will mount. The amount of stretch required would be significant. Using all the steps above we didn't manage to get even half the tire mounted on the rim.

    So, I'm looking for some help here as I really don't want to buy new $700 rims/tires every year when replacement tires are much less expensive.

    Here are the details as accurately as I can describe:
    -The rims are SunRims SW6000, but other than that there are no markings inside or outside of the rim that would indicate appropriate tire size.
    -The tires that came off are 1 inch, and I believe that to be the correct width. The replacement tires seemed like that width would work.
    -The overall diameter of the working mounted rim/tire is roughly 26 1/4".
    -When measuring just the rim from one side to the other it is roughly 24 7/8". This is hooking the tape measure on the outside of the rim and measuring straight across the wheel hub to the other side. Could be 1/16 - 1/8" shorter as the incline of the spokes adds just a bit of length.
    -When measuring the inside of the rim from one side to the other it is roughly 23 3/4". This is pressing the tape measure on the inside of the rim and measuring straight across to the other side.
    -Rifton advertises the wheels/tires as 26" but that is not the size of the mounted tire (from the numbers on the side of the tire). But, again, I don't think this is accurate as their equipment source is doing some shenanigans with heat to stretch the tires in a way that most people wouldn't be able to do. The replacement tires even feel different. The originals seem rubbery (maybe from the heat) while the new ones are much more rigid.

    So, I'm looking for some help/suggestions on what size tire might be appropriate based on the above information. I'm hoping there may be a resident tire expert that could help out. Let me know if any pictures might be helpful, as I can certainly do that.

    Great place you have here. Glad I was able to stumble across it.

    Thanks!
    Ryan

  2. #2
    If they give the size of the tire in ISO mm size this is the only reliable measurements. 26" can mean anything to anybody and is in no way specific. If you say 26" to a bicycle shop they default think about something that is drastically different from what a wheelchair vendor sells as a 26" wheelchair tire.

    In general
    501 mm wheels are sold as 22" wheelchair size
    540 mm wheels are sold as 24" wheelchair size
    559 mm wheels are sold as 25" wheelchair size (but I think this is commonly referred to as 26" tires in the bicycle world, not certain on that though).
    590 mm wheels are sold as 26" wheelchair size

    and there are some other odd sizes like 700c, but few people have those because they're massive

    If the old tire has a size on it in mm, go with that size tire and ignore anything that is stated in inches because a 26 x 1 inch tire or wheel isn't specific at all and can mean a multitude of things.

    Sorry I have no idea the actual diameter of any of these wheels and the tires will vary in diameter (especially if not mounted on a wheel or well worn vs new).

    Solid tires can indeed be a huge pain in the butt to get on the rim, but they shouldn't be ripping. It would be absurd if someone is actually heating up tires and stretching them to fit on factory rims... that sounds like a big ole puff of smoke being blown up your rear... why wouldn't they go with a standard size that didn't require special equipment and an extra step to mount?!?!?!?!?!?!?

    I'm not sure why you feel that knowing what tires came off your wheel will influence your answers in any way, but a picture of the sizes on the tires (old and new) might get you a better response. I don't know much about wheels and tires.

  3. #3
    Senior Member NW-Will's Avatar
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    From what you are saying... it sounds like you have 26x1 (25-590) wheels ... what they call 26" wheels in the wheelchair world.

    That would be the maximum diameter you can measure of a full inflated tire on the rim. Just less than 26", I measure it as 25 7/8" .

    Would be interesting to see pictures of the tire you broke, specifically any markings on it. I'd be willing to guess they were 25x1(25-559) (25" wheels in the wheelchair world), I've never fitted solid tires, so that's just a guess.

    SunRims SW6000, just signifies they are double walled wheelchair rims.. they come in 24", 25" and 26" sizes to my knowledge.

  4. #4
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    Welcome Ryan...I’ve been on this forum for a few years...got an almost 15 year old son. He used that same stander until he became too tall for it, but it’s still sitting in our attic upstairs, so I’ve just been to check it. The rims are the same as you’ve described, but I see no markings on the tire itself, so does that mean you can only see the markings once the tire is pulled off the rim? I can tell that they are on there tightly...they don’t budge, do they?!?!?

    (Obviously your daughter must use hers a lot more that my son did...his tires definitely don’t need replacing!).
    Gordon, father of son who became t6 paraplegic at the age of 4 in 2007 as a result of surgery to remove a spinal tumour.

  5. #5
    This page shows the wheel sizes they used: https://cdn-rifton.azureedge.net/-/m...180620T183716Z
    I see 20, 27 and 35.
    And you can call them with the serial number: 800-571-8198 for the correct information.
    I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

  6. #6
    Thanks everybody for the responses. When I get home from work today I'll get some pictures. Not trying to be cagey on not including the tire numbers. I'll include that information as well. Thanks!

  7. #7
    The ETRTO/ISO tire-sizing system is the ONLY consistent cross-discipline tire-sizing system. Sheldon Brown (RIP) offers a glimpse into the nightmare of tire sizing: http://www.sheldonbrown.com/tire-sizing.html

    I run 25-559 (aka 25x1" in wheelchair world, 559=26" in mountain bike world [road bike world is different still], etc., etc.). 25-540 is the most common manual wheelchair tire size (aka 24"). Look for ETRTO style numbers on your tire; only with those can assure a proper fit. Inch sizing varies substantially among closely related uses/disciplines.
    Last edited by chasmengr; 06-26-2018 at 03:06 AM.
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
    <
    UNKNOWN AUTHOR>

  8. #8

    Reply with Pictures

    For some reason my reply with pictures didn't show up. I'll try it again. Here are some links to my pictures on Google drive that show what I'm dealing with:

    Here is a picture that shows me with the unmounted tire and the new one, stretching as hard as I can. We had attempted to stretch the new one with a Porter Cable heat gun and an industrial come-along but you can see that the old one is much "longer" than the new:
    https://drive.google.com/open?id=1D9...F5tcRL7pr6RKxM

    Here is an image of the unmounted tire next to the new one, showing the same numbers on both 24x1 (540 mm):
    https://drive.google.com/open?id=18x...Fnd7gc2KDGqxiF

    Here is the brand (Shox):
    https://drive.google.com/open?id=1ae...SzVgeZ3JUx7FYr

    Here is the outside diameter of the mounted tire:
    https://drive.google.com/open?id=1Zr...JFLXi7XaFB4Aab

    Here is the new tire resting on top of the wheel assembly:
    https://drive.google.com/open?id=19W...x65LBjDbi8yB0u

    Here is the outside diameter of the unmounted rim:
    https://drive.google.com/open?id=1QN...Q8KpZVBxZXvHl2

    Here is a picture showing the new tire inside of the unmounted tire:
    https://drive.google.com/open?id=1Ta...DRtl1zqxLBBb-N

    Here are pictures of the outside diameter tire size of both just lying on the ground unmounted:
    https://drive.google.com/open?id=1hD...3V6go0nhRqlTF1

    https://drive.google.com/open?id=1c2...r3RkUtcT88gRNA

    Here is the wheel model:
    https://drive.google.com/open?id=1XB...WG9fh6ky-FU6hC

    Thanks everyone for your replies. Based on the pictures above it seems that the original tire has been modified in some way.

    NW-Will - It sounds like what you are saying is that the outside diameter of a 26" tire should be roughly 26" (LOL). That would seem to point to the original 24" tires I have having been modified in some way (heat) to force them onto the rim. That lines up with what Rifton told me and also the look/feel of the original tires. If you notice the logo appears much larger on the originals and also the bead seems stretched unnaturally when comparing the 2 tires.

    Gordy1 - We have 2 of the Rifton standers (both K150 versions). When the tires wore out on the original we bound a cheapy on ebay and had it powder coated. Now we have the frame for 2 but she wore out the tires on the new one also. So, we have 2 sets of worn out rims/tires. The one that we got new had the Shox tires with the 24x1 (540 mm) labeling.

    nonoise - thanks for the link. That is interesting. When I called Rifton and they gave me a quote for new rims/tires it showed 26 inches on my quote. Which contradicts the literature here. The actual diameter is about 26 1/4" (maybe a hair less accounting for the angle of the spokes and the tape measure.

    Thanks for the link chasmenger.

    Does it seem like from the pictures that our rims are really 26" and the original tires have been somehow modified? The difference between the old and new tires is substantial. Plus, the outside diameter of the mounted tire is just a hair over 26". That makes me think I should try ordering a 26x1 (590) to see how it goes. Is there any way to measure the rim itself and know for sure what tires are needed?

    Thanks!
    Ryan

  9. #9
    Ryan, your original post (and second one) did not show up because for new members, posting a response with a lot of external links is flagged as spam by the software, and needs to be approved by a moderator to appear. I will remove the duplicate post once you see this message.

    In addition, there is a way to put your pictures directly onto your post from your computer without posting links. Here is the information: http://sci.rutgers.edu/forum/showthr...-Where-to-post

    (KLD)
    The SCI-Nurses are advanced practice nurses specializing in SCI/D care. They are available to answer questions, provide education, and make suggestions which you should always discuss with your physician/primary health care provider before implementing. Medical diagnosis is not provided, nor do the SCI-Nurses provide nursing or medical care through their responses on the CareCure forums.

  10. #10
    Got it, Makes sense. Thanks a lot for the info about pictures!

    Ryan

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