Thread: DIY Run flat trolley wheels.

What could be easier, drill a couple of holes and pump tyre full of polyurethane foam.

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The cheapest expanding foam I could find, $14 for 750

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Drill 2 8mm holes on opposite sides of the wheel at the high spot in the side of the tyre. Make sure you drill into the inner tube.

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Shake the can and fit the nozzle into the tyre and make sure it's in the inner tube. Keep filling till foam starts coming out the other hole.
Then plug the holes with something, I used 8mm cap screws that were handy.

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The foam keeps coming out for a long time afterwards. The excess should just cut off.

Now, I'll have to wait till tomorrow to clean it up and see if it worked.

Did it only take the one can to fill? Is that the same stuff they use for emergency flat tyres?

I wonder what the load rating will be and if the foam will ever crush or breakdown with tine & use?

Originally Posted by DSEL74

Did it only take the one can to fill? Is that the same stuff they use for emergency flat tyres?

I wonder what the load rating will be and if the foam will ever crush or breakdown with tine & use?

No the stuff used for emergency flat tyres is different, so I'm told. One can was enough.

As to durability, I'll know the answer to that after I've used it for a while,

I did find on-line a guy who used the technique on his ride-on mower, and others who used it on wheelbarrow wheels and trolley wheels.

Ok looking forward to hearing back from you on the results.

Instead of drilling a hole in the tyre, why not just take the valve out of the tube and poke the nozzle in there?

Originally Posted by Pete F

Instead of drilling a hole in the tyre, why not just take the valve out of the tube and poke the nozzle in there?

You need two holes, because you want somewhere for the air to come out as you fill it. And the valve isn't at the high spot. But the real reason I drilled holes is that the tube is 8mm diameter and wouldn't fit the valve.

Wondering why they leave the dead inner tube in? That sort of complicates the fill, if that's inside flopping around. And you have to inject into that. I'm guessing the answer is the bare minimum of work.

I'd predict an even better job, just injecting into the outer tyre. Its not like the tube is doing a lot to expand the tyre if you have drilled 2 x 8mm holes in it. I'm guessing at that point in time, if you have to go to the trouble of de-mounting the tyre, its a toss up to squirt it, or put a new tube in.

Regards Phil.

Originally Posted by RayG

I have a cheap trolley with pneumatic tyres that gives me grief whenever I go to use it the tyres are always flat, so I have to rummage about and find the tyre valve attachment for the air hose, pump up the tyres, which I hate doing, since one exploded on me a few years back.

Sick of low quality "easy burst" tyres & tubes, I bought a non-pneumatic "spongey" wheelbarrow tyre for $30.
It's OK, stays round even if left with a load on it for days. A little more rolling resistance, but acceptable.

Jordan

Originally Posted by Machtool

Wondering why they leave the dead inner tube in? That sort of complicates the fill, if that's inside flopping around. And you have to inject into that. I'm guessing the answer is the bare minimum of work.

I'd predict an even better job, just injecting into the outer tyre. Its not like the tube is doing a lot to expand the tyre if you have drilled 2 x 8mm holes in it. I'm guessing at that point in time, if you have to go to the trouble of de-mounting the tyre, its a toss up to squirt it, or put a new tube in.

Regards Phil.

Maybe it helps with clean up if you want to later remove the tyre an go back to original. All the foam muck is in the tube hopefully and not all over the rim?? Also I think trolley rims are usually two piece bolted together so maybe it leaks?

Only reasons I can think of or yes your correct laziness.

Originally Posted by Machtool

Wondering why they leave the dead inner tube in?

Only reason that I can think of is if tyre is not tight against the rim (which they are not when flat) there will be stuff leaking everywhere. Filling into a tube would contain it.

Michael

Originally Posted by Michael G

Filling into a tube would contain it.

Not an issue, but I'm having a hard time picturing that. You drill one 8 mm hole, then do the other. That tube is flaccid. To do the other hole, you need to drill that into a collapsed bladder, that will only happen when you pin the inner tube to the rim of the hub? Because that's just wanting to flex away from the drill. I'm having trouble seeing how you can drill into both sides. First one is easy. Second one you have an deflated balloon.

Originally Posted by DSEL74

Ok looking forward to hearing back from you on the results.

me too...i have a sack truck that needs a new tube....might not need to that?

True, but I would not be doing this anyway because the foam you get in a can is rigid. I suspect that after a bit of heavy use you will have crushed the foam around the outside of the wheel and it will be like a permanent flat with no way to re-inflate. For this to work properly it would need to be a flexible foam but reasonably stiff.
I wonder whether a two part urethane rubber mix about 70 duro would be better.
When I worked at Holdens to fill the brake system of a commodore they would pull a high vacuum on the complete system at the reservoir and then introduce the fluid - no bleeding required. Perhaps something along these lines to fill the tube - pull a vacuum on the tube and then pump the foam (or fluid) into the tyre once there is no air in it. It's getting complicated again!

Michael

Of course, you could just by some solid wheels and replace the pneumatic ones...

Originally Posted by Machtool

Not an issue, but I'm having a hard time picturing that. You drill one 8 mm hole, then do the other. That tube is flaccid. To do the other hole, you need to drill that into a collapsed bladder, that will only happen when you pin the inner tube to the rim of the hub? Because that's just wanting to flex away from the drill. I'm having trouble seeing how you can drill into both sides. First one is easy.
Second one you have an deflated balloon.

They were already completely deflated.

When I was drilling the holes, the inner tube wrapped itself around the drill bit and I had to go back and forwards a few times, but I just checked the tyres a little while ago and they still seem soft, I would have thought it would be hard by now? If it hasn't worked by tomorrow, I'll pull the tyre off and see what gives. Maybe it all went on the outside of the tube after all?