WheelchairDriver

Posted: **03 Sep 2025, 16:27**

Hello.

I need to replace the front wheels of my old chair.
Today it has pneumatic wheels with measures 200 x 50.
Im looking for compatible solid wheels.
The solid wheels with size 200 x 50 do not fit; they are larger than the air ones.

What scale of measurements do the wheels follow?

Posted: **03 Sep 2025, 19:33**

From what I'm seeing the scale (outer diameter) is in inches.

4", 5", 6", 7", 8", 9", 10", etc

200x50 (cm) = 8x2 "

The immediately smallest wheels (scale) are 7 inches in diameter.
I'm looking for something in between, but it's not manufactured.

Posted: **03 Sep 2025, 21:07**

Several problems...

Metric and imperial. Those tyre descriptions are different in how they all work.

Tyre sizes are NOMINAL and not exact.

An imperial tyre such as a typical rear tyre on a chair will be 3.00 x 8. Its REAL description in full is 14 x 300-8 Or 14 (OUTER DIAMETER) X 3.00 (WIDTH) - 8 (RIM DIAMETER) Where did 14 come from? Sidewall is 3, + rim is 8, + sidewall other side it 3...

So if you see a caster tyre that is say, 3 x 4, or 3.00 x 4, it really means its TEN (10") outer diameter, and 3 inches wide, and fits a 4 inch diameter rim. It SHOULD be called in full, a 10x300-4 tyre. It would need a 2 inch WIDE rim.

A low profile imperial tyre is usually described as say 300 x 260 x 4 for an example. That just means its: 3 inches wide. Has a 2.6 inch sidewall. And fits a 4 inch rim. It SHOULD be described as a 9 x 300/260 - 4. All sizes here are NOMINAL and approximate. Except the rim size and thats exact.

If its a METRIC tyre, it will be sized in Millimeters wide, and % sidewall and inch diameter!

So a 120/70 - 8 tyres such as I use on my Salsa chair, is 120mm wide (about 4.6 inches? Has a sidewall that is 70% of that 120... So an 84mm sidewall. Its total diameter is the 8 inch rim, (200mm) + 84 + 84 - 368mm (or 14.5 inches.)

Does that help?
When I see a tyre advertised all that goes through my head. czy

Posted: **03 Sep 2025, 21:11**

Life is very complicated...

Posted: **03 Sep 2025, 21:15**

Well its either simple and wrong, or complicated and correct.

Everyone wants a simple single line easy answer. Thats not how life is.

Its not just tyres. Its everything.

When you know very little you think that everything is simple. When you ask a question, and the answer just makes you have many more questions that just shows that you are leaning stuff! Like how much mre there was to know. The more you learn the more there is to learn! Unfortunately thats how life is.

Posted: **09 Sep 2025, 02:59**

And of course just to make it more complicated yet, as BM mentioned, except for the rim diameter, the sizes are NOMINAL, which means the actual size is NOT going to be what is on the sidewall, but something that is sort of close, but could be bigger or smaller...

On top of that a pneumatic tire will vary in it's inflated size (both width and OD) depending on the width of the rim it's mounted on. Solid tires have a different problem in that most don't tell you the rim width they are intended to fit, but are very much limited in what width they will work on... Same nominal size Invacare tire is to narrow to work on my Jazzy wheels, and the Jazzy tire is to fat to let the rim halves on an Invacare wheel mate up....

Have fun trying different tire / wheel combos to get something that fits....

ex-Gooserider

Posted: **13 Sep 2025, 17:57**

My Invacare Mirage uses 7” solid wheels (really bad quality) and I switched to 8” solid with no problems, I didn’t feel they were so different. But now I have a new Q300R with also 8” solid tyres and they look much bigger.

Posted: **13 Sep 2025, 18:09**

8 solids? On a 300R with no front suspension? That will rattle your fillings a bit.
I got solids on the Dietz since it is 4mph as I refused to pay the difference. And only use it around the house. I have other chairs for out in the world. But it was a mistake. That 4mph feels like 2. And the solid tyres feel like iron. If I do this again I will have pneumatic regardless of the extra maintainance and will pay the extra for 6mph so I dont die of boredom even in the house. Its lack of speed is remarkable!

Posted: **13 Sep 2025, 20:48**

Burgerman wrote:8 solids? On a 300R with no front suspension? That will rattle your fillings a bit.
I got solids on the Dietz since it is 4mph as I refused to pay the difference. And only use it around the house. I have other chairs for out in the world. But it was a mistake. That 4mph feels like 2. And the solid tyres feel like iron. If I do this again I will have pneumatic regardless of the extra maintainance and will pay the extra for 6mph so I dont die of boredom even in the house. Its lack of speed is remarkable!

You are right, I feel every bump of the street. But I wil never go to pneumatic again, it was a nightmare with flat tyres. I ordered the chair with 8” instead of 9” because I felt 9” too big for indoors. Do you recommend I change to 9” solid?
Furthermore, I have 12,5” back, for the same indoor reasons.

Posted: **13 Sep 2025, 23:33**

I have 9 solids on the Dietz. Its murder - SOLID Is SOLID...

I am going to stick to pneumatic. A world of difference.

If you think the pneumatic tyres are a problem is that because punctures? Because I just ignore them and keep on using it...
Or because they deflate over time? Because properly installed GOOD tubes, quality valves, and some sealer and they just dont!

Posted: **14 Sep 2025, 07:48**

faico_26 wrote:I feel every bump of the street. But I wil never go to pneumatic again, it was a nightmare with flat tyres..

I have the same experience with Burgerman's that a flat caster won't stop driving, but went miles and miles unnoticed, because they don't carry most of the load.
Otherwise, your chair is not setup properly and nose heavy.

Most people never know how good it steers and handles curbs when it isn't nose heavy.

faico_26 wrote:By the way, my VR2 is 90amp and as I have explained in this forum before it stops the motors when facing a tiny 3cms curb. .

Posted: **14 Sep 2025, 15:05**

Burgerman wrote:I have 9 solids on the Dietz. Its murder - SOLID Is SOLID...

I am going to stick to pneumatic. A world of difference.

If you think the pneumatic tyres are a problem is that because punctures? Because I just ignore them and keep on using it...
Or because they deflate over time? Because properly installed GOOD tubes, quality valves, and some sealer and they just dont!

In the past I used pneumatic in 4 tyres. Most problems were with front tyres, constantly deflate and sometimes punctures. Then I moved to solid and never had a problem, but my old Invacare Mirage is slower and much lighter than my new Q300R. With the Q300R I feel every bump on the street, driving is much uncomfortable. I will think about pneumatic. Probably it will help me to climb curbs too if rear wheels are pneumatic?

Posted: **14 Sep 2025, 15:30**

For rear wheels the best solution is to use quality tubeless pneumatic tires and sealant on rims designed for tubeless tires, but that requires making an adapter to fit the new rims to the motors. Several of us have done this and I don't think anyone's had a flat in many years of using this setup.

Posted: **14 Sep 2025, 17:28**

LROBBINS wrote:For rear wheels the best solution is to use quality tubeless pneumatic tires and sealant on rims designed for tubeless tires, but that requires making an adapter to fit the new rims to the motors. Several of us have done this and I don't think anyone's had a flat in many years of using this setup.

I would love to use tubeless but I don’t think I can get everything I would need to install them.

Posted: **18 Sep 2025, 21:03**

Burgerman wrote:I have 9 solids on the Dietz. Its murder - SOLID Is SOLID...

I am going to stick to pneumatic. A world of difference.

If you think the pneumatic tyres are a problem is that because punctures? Because I just ignore them and keep on using it...
Or because they deflate over time? Because properly installed GOOD tubes, quality valves, and some sealer and they just dont!

Hi,
Any recommendation on where to buy good tubes, quality valves and sealer?

Posted: **18 Sep 2025, 21:34**

Hi,
Any recommendation on where to buy good tubes, quality valves and sealer?

Look for tyres, tubes and sealant for industrial use.
I've given up.

Until 5 years ago it was possible to buy 8 inch (black) industrial tyres.
Impact manufactured high-quality industrial tyres.
Now those same industrial tyres are shit.
I don't waste any more time and money on buying shit.

Which tyres are you looking for?

Posted: **18 Sep 2025, 21:49**

Buy branded tyres from repuable sources.
Such as the Duro ones on my chairs. Those cost. 5X as much as the rims!

The problem is that any idiot can take a high quality tyre with superb belted reinforced steel and kevlar, well researched and evolved rubber formulations etc. And make a really crap cheap copy that on the outside LOOKS the same. Using the quality tyre as the thing to make the mould so even the branding may be the same. Sometimes they change the design and add a new name. So they cant be shut down for copyright infringement. In cheap china everything gets copied. You can buy a 5 series BMW which has low fidelity, and terrible build quality! It even looks crap!

I tend to get tyres from places like:
https://www.shirebikes.co.uk/collections/tyres-tubes for my duro ones
Or https://allterraintyres.co.uk/index.php ... =1584_1585

Etc.

WheelchairDriver

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