Repairing small wheel tire flat spot

[soldar]

I have one of those small luggage folding carts and I used it to move a (very heavy) server for a few blocks.

At some point the server touched and blocked one of the wheels so that it was dragging along and it wore out a flat spot. It is solid black rubber.

Now when I use it the flat spot makes it bump with every turn of the wheel.

What would be an easy (and cheap) way of repairing the flat spot?

Maybe build it up with some type of caulk? But I doubt it would last.

What would be the best product?

[Domagoj T]

It obviously depends on the depth of the flat spot, but if you can have it turned on a lathe, it would be as good as new.

[soldar]

That would not make sense because I would have to reduce the diameter of both wheels. And I don't have a lathe anyway.

What I'd like to do is build up the flat spot. It doesn't even have to be perfect. Just avoid the hard bump each turn of the wheel.

[Gyro]

Find another (pair of) wheels? There seem to be all sorts of different ones cheap on ebay and amazon. As long as the hole diameter is the same you should be fine. You might well find better ones.

It sounds like less effort and more likely to succeed than trying to build up a rubber tyre.

[Dundarave]

If you are going the build-up route, consider using “Shoe Goo”...  It hardens up very tough and adheres very well.  Put a tight round paper form around the wheel, and drip the stuff in at the flat.

The Goo is very viscous initially, but will level like water before it hardens (and will likewise find a way to leak out of the form).

But it’s great for re-building up worn sole areas on your favorite trail runners...

Alternatively, perhaps you could just file down the round-to-flat transition and make the wheel more oval, as it were.  At least it wouldn’t “thump” as much.

[Tomorokoshi]

Post a picture of the damaged wheel.

[soldar]

If you are going the build-up route, consider using “Shoe Goo”...

Thanks! I had never heard of that stuff. I might give it a try.

I am also thinking I have nothing to lose if I use some old epoxy which is getting so old I'll soon be forced to throw it away. It's not rubber but it should help make the wheel more round. Maybe drive two or three small screws into the rubber so the epoxy can grab them even if it does not stick perfectly to the rubber.

Obviously this is just for entertainment. I can buy a new cart for so little it would not be worth the repair.

Still, that Shoe Goo looks like interesting stuff to play with. I'll give it a try.

[Mr. Scram]

That would not make sense because I would have to reduce the diameter of both wheels. And I don't have a lathe anyway.

What I'd like to do is build up the flat spot. It doesn't even have to be perfect. Just avoid the hard bump each turn of the wheel.

What's wrong with reducing the diameter of both wheels? It's almost certainly a more durable solution than filling the gap, providing the functionality doesn't get impacted by smaller wheels.

[soldar]

Reducing the diameter is more complicated for me and would take away about half of the rubber's thickness. I would rather build up if I can.

[Halcyon]

Could you not just replace them with a cheap set of rubber air-filled tyres?

[soldar]

I do not think they make air filled tires so small. It is a light weight folding cart, not a real man's sturdy, bomb-proof cart.

I could probably find similar wheels if I looked for them ... and I could probably buy a new cart for the same or a little more.

Mainly this is an exercise in doing the rubber repair and gaining some experience. That Shoe Goo looks like an interesting product I'd like to try on different uses.

[MyHeadHz]

Another option would be to notch it (like a dovetail) with other rubber and then use a rubber adhesive.  This would be better and permanent, but it would take more effort and something to sacrifice some rubber off of.

[Rick Law]

I too like to repair things for fun...

Go to a bicycle store (or auto parts store) and get a tire-repair kit.   For bike tire repair kits, it is typically patch types .  For auto tire repair kit, there are two kinds, most are plug based - it comes with a plug to plug the hole, so look for the kind with a patch sheet of rubber which used to be common but less so now.  Acto-knife (and/or drill bit for grinding) to reshape it back into a perfect wheel.
Bike tire repair kit example from Walmart (USA)  Since you are not in USA, you may have similar kind of stores:
^{https://www.walmart.com/ip/Sunlite-Bicycle-Tube-Patch-Kit-Small-Plastic-Case-7-Patches-Glue-Scuffer-Bike/41874413}
-or-
If you have access to a lathe, cut a new wheel with wood and then tread it (see also RETREAD below).
-or-
Completely (or just the mis-shaped area) retread the tire with use (or new) bike tire.  If you are retreading, it is probably best to put new treads on both wheels so they are a balanced pair.  Retreading is common with truck tires (in the USA anyhow) since truck kind of consume their tires like programmer consumes coffee.
^{More info on retread:https://en.wikipedia.org/wiki/Retread}
-or-
Take it to a bike repair store, tell them, repair this damn thing and I'll be back to pick it up in two hours...

(Endless possibilities...)

[Nominal Animal]

I wonder if Sugru or Loctite Kintsuglue or similar rubbery putties would work?  Or last.

[duak]

In an emergency I've retreaded a rubber faced wheel by using Shoe Goo to hold a flat rubber belt on.  It was hell to get the belt on, but it did work.

[tooki]

Wheels don't cost very much.

But yeah, if you can get pneumatic tires, that's definitely better. What diameter are the wheels?

[soldar]

I wonder if Sugru or Loctite Kintsuglue or similar rubbery putties would work?  Or last.

I've thought of adding a layer of rubber glued with contact adhesive and then filing it down to shape. Maybe add two or three screws to hold it in place. I could use rubber from an old tire or shoe. Maybe use that Shoe Goo instead of contact adhesive. Once I have the "ingredients" I'll give it a try.

I have a much clearer idea of how to proceed now.

[soldar]

If you are going the build-up route, consider using “Shoe Goo”...  It hardens up very tough and adheres very well.  Put a tight round paper form around the wheel, and drip the stuff in at the flat.

The Goo is very viscous initially, but will level like water before it hardens (and will likewise find a way to leak out of the form).

But it’s great for re-building up worn sole areas on your favorite trail runners...

I used Shoe Goo and it worked well. I did not make a mold like you suggested. I put some thumb tacks in the lowest spot, just to build it up a bit, and then added the shoe goo in several layers. it is not perfect but the wheel works fine, without the thumping.  Thanks for the suggestion.

I might try using it for shoe repairs where I would normally have used contact glue.