3.5" tubeless tires

[hobie1dog]

Shirley- I think this is the same as your first set of 8 X 2.00-5 tire/wheel set you posted the pictures of.

https://www.aliexpress.com/item/Solid-T ... .15.toIQHk

My stock pneumatic tires (that are 3 months old and leaking) are 7.5" tall, so these 8" diameter tires being the same 2" wide will work fine. I would have to drill new holes in the caster forks, up about 3/4" to allow for the overall increase in size. Funny though the ad lists them as "Solid tubeless "

Sad thing is the price is $17.64 each, but you get charged $20.74 in shipping. Order 2 of them and they hit you for another $20.74 in shipping totaling $56.03

You get a whopping $1.00 off an order of $50.00, how incredible of an incentive......NOT

[ex-Gooserider]

Most times I've found LOTS of vendors for a given item on Ali Baba or Express... If you find an item you like but not the terms or price, do some more searching using that item's description.... Check other vendors.... Also try contacting the vendor and asking them about the pricing - it may be an error in the way they set up the listing, and they will really offer a better deal on two if you ask...

ex-Gooserider

[shirley_hkg]

TUBELESS

Looks like the pictures didn't transfer but it was the top set of Silver rims w/ 8 X 2.00-5, the three spoke wheel.

Where did you find these at? I didn't find those pictures anywhere when searching those would replace the stock pneumatic tires on my S636 without changing the forks and give me tubeless

We find it not good , as it seals only at pretty high pressure .

[hobie1dog]

TUBELESS

Looks like the pictures didn't transfer but it was the top set of Silver rims w/ 8 X 2.00-5, the three spoke wheel.

Where did you find these at? I didn't find those pictures anywhere when searching those would replace the stock pneumatic tires on my S636 without changing the forks and give me tubeless

We find it not good , as it seals only at pretty high pressure .

you would think in this day and age, with hundreds of small tires and wheels out there, that we could find a tubeless tire and wheel that would work for us.

[hobie1dog]

THEY are tubeless , whereas yours are tubed . That makes a huge difference . Puncture seal never work on tubes .

But John does this on his BM, correct?

So unless someone discovers a small tubeless front tire, we are stuck using tubed tires that will leak.

Pretty disappointing.

[Burgerman]

I use tubeless on the rear.

For casters I use tubes but add some puncture seal just in case. Because my casters are lightly loaded they tend not to puncture. They float over stuff. And dont wear fast. And also they can run at very low pressure. And punctures then dont matter anyway. This was worn until it popped the tube! And still got me to the pub and back for a few days.

http://www.wheelchairdriver.com/gopro/puncture.mp4 So I don't much worry about those!

http://www.wheelchairdriver.com/gopro/soft.mp4 Why fat 10 inch casters (that are lightly loaded, because of rearward CG position), meaning they can be at low pressure work well... These are at around 6 psi.

[hobie1dog]

Thanks for the video. When I flip my joystick to the left or right (from a standstill), there is a big delay from the front tires having to overcome the change of direction, then after they get turned, there is an increase in speed. This usually causes the chair to lunge in the new direction, marking up walls or hitting something. My mid wheel drive chair is much more suitable for indoors. I'm pretty unhappy with this 636.

[expresso]

Thanks for the video. When I flip my joystick to the left or right (from a standstill), there is a big delay from the front tires having to overcome the change of direction, then after they get turned, there is an increase in speed. This usually causes the chair to lunge in the new direction, marking up walls or hitting something. My mid wheel drive chair is much more suitable for indoors. I'm pretty unhappy with this 636.

you would feel much better if its adjusted to you better than its stock form - its a change from your previous chairs - indoors needs to have more careful use of the JS -


how do you feel about it outdoors ? are you just unhappy indoors with the chair ?

[Burgerman]

Thanks for the video. When I flip my joystick to the left or right (from a standstill), there is a big delay from the front tires having to overcome the change of direction, then after they get turned, there is an increase in speed. This usually causes the chair to lunge in the new direction, marking up walls or hitting something. My mid wheel drive chair is much more suitable for indoors. I'm pretty unhappy with this 636.

Thats because of programming. Its NOT the casters. Once PROPERLY programmed it makes absolutely no difference where the casters are pointed. And you wont be able to tell. The chair just goes where you tell it, when you tell it, and at the rate you previously told it to. Not faster or speeded up turn later. You will not ever think about casters. But its extremely unlikely a dealer can or would be able to do this.

This is MY idea of too much delay, and soggy programming. I reduced a few settings from 100% down to 90. And didnt like it because its harder to steer accurately. http://www.wheelchairdriver.com/gopro/control.mp4

Play twice. 2nd time watch only my hand/thumb. And the chair response. This is 6mph with wheelies, max acceleration, indoors through a doorway that is only 2.5 inches wider than the chair.
I drive this way 24/7 for 20 years. And never hit a thing yet. The dog came close but he knows, so I shoved his head out of the way. While wheelieing, while going through a doorway... Seriously. Thats a 10 year old, 80A chair, rear drive chair with 10 inch casters, mostly airborn. With tired batteries, and a 20 stone 57 year old user. A newer one with fresh batteries, and with newer motors, and 100A controller is a lot sharper. And easier to drive. Of course you dont need to drive this way. The accuraccy remains regardless. Its inch perfect and exactly consistent, and linear.

There isnt a stock production chair, or a dealer programmed chair. that I can use. None. They all feel like you are trying to drive a hovercraft. However ALL chairs, mid, rear, can be programmed to steer properly. With the exception of front drive.

[shirley_hkg]

And his chair has too heavy nose undoubtedly .

[Burgerman]

It shouldnt matter that much. But it wont help!

[expresso]

well cant do much about the chairs how we get them - if he has a factory tilt on it - if they set it up correctly - it would or should be sitting back near the rear - depends how his seating size - few other things

my chair has a motion seating- and its as far back as it can go - - if it didnt have the motion seating lift tilt etc, - and just a factor sunrise tilt - it could sit back a few more inches easy - this will all depend how the vendor salesman configured it and also how much user input was involved also -

overall i think the 636 - chairs are the best in that dept. compared to other RWD chairs - not many to choose from

[LROBBINS]

There are several things that can contribute to this, not just too little acceleration:

(1) As Shirley notes, too much weight on the casters will definitely give the problem of their not turning and then jerking around sharply. This is definitely the case on my daughter's chair (though the CG in her case is too far aft - it's a front wheel drive with 30% of the weight on the rear casters). If it is at all possible to move the 636's CG back, it should help. With the driver being a large weight, even moving the seat back a little bit can help a lot.

(2) Too low caster tire pressure. Again, this is very much the case on Rachi's chair. Anything less than 20 psi causes exactly that behavior. At 20 psi it's OK on solid surfaces, but still balky on short nap carpet. Better for that at 30 psi, but 20 gives better shock absorption.

(3) Too low turn acceleration. Power builds slowly and nothing happens, so the stick is pushed further over and finally the power goes up and whoosh.

(4) Too low motor compensation. This will do as in (3), but careful - too much compensation will make the turn start more easily, but also increase the tendency to move abruptly afterwards. Even more compensation and one can get a runaway where centering the stick won't stop the movement.

In any case, both the physical arrangement and programming can and will contribute to this and you have to work on both.

[Burgerman]

I agree on all counts. Except that I think that from experience its almost always 90% programming. (motor compensation, turn acceleration and turn deceleration, damping, any settings that "round" out transitions, or smooth the transition from full turn acc to non or that smooth the transition from no turn to full turn. (that remove the "abrubt" changes of pulsewidth etc).

For one, because I lost count of the number of times I reprogrammed chairs for people that travelled here for this very reason, and at least 7 from this forum alone, and that behaviour just vanished. For eg my chairs all steer straght away, in a very linear fashion, even if I let all the air out of both front tyres. Yes you need more stick, in that case, but theres no wait, no delay no overshoot, no whoosh. It just does wbat you expect. But it now requires slightly more "stick" depending on where they point. Thes is just "feel" that is lacking on brushless/gyro assisted setups. The point being theres no "wait" (delay) as described by the original poster. If you can "feel" a difference between rear drive and mid, then you have a programming problem. You shouldnt be able to. AndI am 20 stone, thats 3x heavier than rachi is! And weight makes a huge difference. And I have no issues.

Theres 2 other possibilities. Which I suspect rachis chair has, esp since she is light. So this should just not be an issue. And that is that the motor impedance is so high that no amount of compensation can get rid of the delay since it has to change pulsewidth by a very large margin which takes time. Or never achieves a high enough current at all. That is unusual with modern chairs.

OR that the motors do have enough power (low impedance) but the power module itself, or batteries, cannot provide enough Amps. You NEED around 100A controller on a 6mph chair minimum. Or MOTOR Amps get maxed out on every turn in space.

But as you say all these things, CG, proframming tyre prssures etc do have some affect. I just feel that once I am let loose with a programmer that most users will never notice it or rather be bothered by it again. My casters for eg, have 5 to 6 psi. I cant tell any difference between that and 30 psi in steer or control response. Motor compensation makes the Amp adjustment on my behalf.

[LROBBINS]

You are probably right that programming is the most common issue; certainly with lightly-loaded casters not much else will matter. However, that's not the case on Rachi's chair with 30% of the weight on the casters when in trail, and substantially more when going backwards.

Motor impedance is high - 105 milliohm, but not astoundingly so. For everything except turn-in-place motor compensation at that level is quite adequate.

The controller has no problem putting out enough amps - I have the amps limit at 130, and current never gets limited except if the caster really can't turn. It's pretty obvious when there's roll back in that case.

Adding extra motor compensation for turn-in-place, without dealing with mechanical issues, did mostly eliminate the turn-in-place problem, even with tire pressure < 10 psi, EXCEPT on difficult surfaces, with Rachi tilted back and after moving backwards so that the casters had even more weight on them - never measured but probably close to 50% of gross weight. Even with boosted compensation, I don't think that time to reach PWM is really an issue. With motor resistance for turn in place at 150 milliohms, at 100 amps, Steering will be boosted from its 17% (min pot, maximum throw) to 32%. With turn acceleration at (TurnBoost=3)*(Acceleration=210.0) = 630.0 it will take about 1/2 second to reach 31.5% PWM. In any case, bringing tire pressure to 20 psi essentially resolves the problem - there's no hesitation for t.i.p. as long as the stem bearings haven't yet failed.

BTW, You have several times brought up the Roboteq's "Short circuit protection" and "Stall Detection" configuration parameters. According to the Roboteq manual, "Short circuit protection" will not act unless there's an extremely low impedance short in the wiring - even a short within the motor will not trigger it, and drawing too much current by a normal motor certainly will not. It has to be a short between Batt+ and Batt- or between a motor wire and Batt-.
"Stall Detection" is different, but it applies ONLY to brushless motors or brushed motors equipped with an RPM sensor (encoder or tach) and, according to the manual, then only in closed loop speed mode. It depends on seeing RPM stay at 0 while PWM > threshold value for threshold time, but on brushed motors without an RPM sensor this parameter doesn't do anything at all.

I think I've finally solved the caster stem bearing problem, but not in the way I'd expected to. As originally supplied the chair had what can only be described as furniture casters - an un-bushed steel-on-steel kingpin, a stamped-race thrust bearing, and solid wheels. I had long ago replaced that with two deep-row radial bearings and real wheels and tires, which worked much better, but had a durability issue. The stem is 12 mm and the bore is all of 14 mm - there is simply no room for a spacer so all of the axial load is taken by the lower bearing and they failed repeatedly. I probably could bore this out, but have been wary of doing so because I don't know if this mightn't be a porous casting and much weaker than it looks. Every time the bearings started to go, the first symptom was difficulty with t-i-p.

I recently tried replacing the lower bearings with angled-race bearings, but the only affordable ones I could find were Enduro max 7001-2RS. These are only 15-degree and have an (unusual) full race of balls. With the stem nut tightened only enough to keep the stem vertical, they turned freely, but once the jack was lowered they simply locked up with the weight of the chair. No help at all.

What I've done now is to replace the wide flange washer that sat between the fork and lower bearing inner race with a large bore thrust bearing so that axial load is entirely born by the outer race of the lower bearing. The are kept centered on the stem with some rubber tubing with 12 mm ID and OD matching the thrust bearing. They are open bearings, so I added some grease shields made from plastic drain pipe. Unless they fill with crud despite the shielding, I think this will have licked the broken bearing problem. Tires are smooth 9x3.50-4 with a nearly square cross section and have a large contact patch and lots of scruffing friction even at 20 psi, so there's no shimmy problem at the speeds this chair goes.

As I said in the previous note, the final fix was raising tire pressure to 20 psi. There is some lag on short nap carpet, but otherwise t-i-p is nicely fluid.

[snaker]

Thanks for the video. When I flip my joystick to the left or right (from a standstill), there is a big delay from the front tires having to overcome the change of direction, then after they get turned, there is an increase in speed. This usually causes the chair to lunge in the new direction, marking up walls or hitting something. My mid wheel drive chair is much more suitable for indoors. I'm pretty unhappy with this 636.

Can you post a pic of your current casters? The pic below is my old caster, its wall is squared. After switching to rounded casters, driving is a lot better. I did not know that caster shapes could impact so much on driving. The downside is that rounded casters cause the shake problem more easily then squared ones.
https://goo.gl/photos/j6jqVnTXHndmjB2P7

[Burgerman]

Square(d) casters put a lot of rubber on the ground. So are harder to turn. This is a natural damper. It stops the caster ocillating. Because it resists turning left right all on its own. This is the same reason that lowering tyre pressure makes it less likely to shake. nd harder to turn.

But it means a square tyre has sides that are not in line with anything that they come into contact with while rolling. The contact patch is wide. So they get pushed sideways if you run up against an edge that isnt straight in line with the direction you are traveling in. Like say a longditudinal edge of a paving slab that isnt flush with its neibour. This knocks the caster out of line and makes it slip and go sideways. Instead of rolling up or over the ridges.

[hobie1dog]

I don't have a picture of my front end set up, as PhotoSuckIt ruined my photos.. no doubt that my programming is the biggest cause of the problem. My sales rep came by once and used his programmer and I finally just told him that I would need to put different tires and wheels on it. I'm going to send him John's video to prove my point.
The caster forks are very tall and narrow for the stock tires on this Quickie S636( non-suspension model forks), as these are the basic tires that are only 7.5" tall and 2" wide, that's all Medicaid paid for, and are low in pressure as they leaked a month after I got the chair. He told me all the small tires they use on powerchairs leak. That's why I am still working on coming up with a tubeless front tire/wheel combination. But the chair still had the same problem with incredibly slow response when the joystick was pushed sideways from the first day.
The seat and base they put on this chair is not moveable front to rear, so the chair is very nose heavy. When I first got it, it had a serious case of porpoising. Let off the joystick and it dived forward like you had someone in the back with a big rope stopping you. Before I attempt to have him bring a programmer back here, I need to have different tire/wheel combination up front, likely with the rounded forks that will accept a bigger front tire setup. Then also put on a different seat that I can position rearward to get all the weight off the front end, as all the programming in the world isn't going to compensate for that. You can see on the Sunrise Medical site how far the seat is for this model. Wheelies...impossible like this.

So:
1. CG way too far forward
2. Tires are low
3. Forks are tall/squared
4. Progranmming SUCKS

[Burgerman]

He told me all the small tires they use on powerchairs leak.

Dont listen to fools. All cheap low quality tubes leak as in the air escapes through the rubber. Good quality named brands don't so much. In part because they are heavier and thicker. They also use a blend of materials that help stop it. Or at least they only leak a bit. What is a "bit"?

Air is made from large Nitrogen atoms 79%. And small oxygen atoms 21%. Some of the oxygen atoms can leak slowly over time. And about 3 of the nitrogen ones... And a good tyre sealer can help stop even that. Theres a 10 year old wrecked chair in my garden. Its tyres are lower now than 5 years back when I sent it out to pasture. But I still use it for dirty jobs. And have not checked the tyres.

Actually its not that simple http://www.getnitrogen.org/pdf/graham.pdf
But for the likes of us and our purposes thats how it works.

[Burgerman]

So:
1. CG way too far forward
2. Tires are low
3. Forks are tall/squared
4. Progranmming SUCKS

Sounds like every stock chair I ever tested.

[expresso]

yeah thats true about the tires - if they are Air - they will leak some - but not extreme - i got myself a battery air pump and use that every so often -

i did change my tires to Air from Foam - - but put the larger forks and tires also - not sure how they set your chair up - or how large is your seat - 18 x 18 ?

do you have tilt on your chair ?

i been with Foam tires up to this year and i really didnt have to add Air many times - over the course of the summer - once a month at least check and top it off to what ever PSI you use -

[Burgerman]

Put a tiny bit of sealer in. That should drop to every 6 months at least.

[expresso]

i have some slime in there also - i dont feel too worried about it much now - at first i was concerned but if it behaves this way - its not too bad at all

knock on wood as they say

[Burgerman]

These tyres, two shown here, are hopeless now on wet grass. Ant they are supposed to be turf tyres. But some of the newness has worn off.

[Burgerman]

They looked like this a couple of years back.

[hobie1dog]

yeah thats true about the tires - if they are Air - they will leak some - but not extreme - i got myself a battery air pump and use that every so often -

i did change my tires to Air from Foam - - but put the larger forks and tires also - not sure how they set your chair up - or how large is your seat - 18 x 18 ?

do you have tilt on your chair ?
-

The seat base is a 18x18, with the tilt actuator. There are 3 sets of holes for the rear mounting point of the seat base, which makes it look like you could have 3 seat positions front to rear, but the front has only one set of holes drilled where the strut rods are attached. Even if I had a new set of holes drilled up front to allow the entire seat assembly to be slid back, then those darned swing-aways would hit the front tires. It's a really f~*]ked up design. I had just planned on removing the whole seat assembly and adapting a bucket seat, but it's a shame to have to spend the money and time doing it. I am really curious as to how much the entire seat assembly weighs. Anyone weighed one?

John- I can't believe you wore all the knobs off those tire

[expresso]

just curious if you ever take pictures of the chair - post them -

i have a 646 but its not sunrise seating - i have seat lift and tilt in one unit - and thats mounted on the chair base - its as far it can go because it needs the room for the rest of the stuff - - if not for the seat lift and tilt etc, - i could have maybe gotten it back further maybe all depends


the stock programming wasnt too bad on my chair - but much better now after programming - i actually had to slow some settings down - accelerations were too high - - remove some delays on turning - and max out the turning accelertions - not the turning speed -

i didnt make many changes - left it alone -

curious if you ever get a programmer to check it - curious to know what the stock motor comp. is set at - Mines was at 30 - and feels fine - i tried 35 and 40 but went back to 30 -

we do have different motors - speed wise - wonder if that makes a difference

[expresso]

do you think having the suspension forks would help ? i went from suspension to Fixed fork with larger tire with Air -

[Burgerman]

John- I can't believe you wore all the knobs off those tire

Those turf tyres wear out very very slowly. I thought they were going to last forever. That was a supreme effort and the chair wore out at the same time. It only ever had the one set of rear tyres. The whole thing is as tired/bad. But they are k-sheild tubeless. Not a single deflation in 3 or 4 years of daily abuse when my dog needed or wanted 5 miles a day minimum on rough tracks and streets. And thats the 2nd chair that I wore out a set of those on. But they are long lasting and reliable.

Last winter in the snow they were worn as you see. That worked "well"... As long as sitting in one place was the plan. Those are great on snow normally with tread. But the kojak look sort of ruined that a bit.

I have a habit of wearing out tyres. I do a lot of miles! These 10 inch caster tyres were worn till the tube popped through the casing, and wore itself out on the road... And I still didnt swap them for another week. You can drive like that.

http://www.wheelchairdriver.com/gopro/puncture.mp4

In happier times they looked like this (I buy 4 or 8 at a time as these do wear fast!) :



You gotta get your moneys worth! Seriously, dont wear them to this level, I am stupid enough to do it. But they perform badly and are more likely to fail.

[hobie1dog]

John - can you give us a site that we can buy the same tires as?

Also will need to have some programming parameters to go by once I get the dealer back up to program.
Like turn acceleration rate, normal acceleration rate, decelerate rates, etc, I want to be able to tell him what the rates I want knowing they work for you people.