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I recently inflated a tire to 50 PSI. The tire/innertube is recommended to inflated to 30 to 80 PSI (standard tires on RadWagon 3). At 50 PSI however, the innertube started bulging to the point that the tire bulged. After deflating it to 30 PSI, the bulge disappeared and the tire now looks normal again. In the past I noticed the same innertube / tire gradually losing air over time.

I'm now somewhat worried that the innertube is damaged and there is a chance of catastrophic failure. Should I go ahead and replace the innertube or is it safe to ride as long as there is no bulge visible at current inflation levels?

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    The biggest danger is that the tire has become off-center on the rim. I would generally deflate it, "jiggle" it on the rim to make sure it is centered and evenly seated, then re-inflate. Sep 19 at 20:11

4 Answers 4

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The tube holds the air, the tire holds the pressure. A bulge is entirely a failure of the tire. If the tube remained intact then the tube is fine.

I would not ride a tire that had bulged as you described without identifying why. If, as suggested by @Criggie already, the tire was not seated properly, then reseating will fix it. If on the other hand it's a failure in the tire, there's nothing to stop that failure occurring at lower pressures and while you are riding.

Deflate the tire, work the beads and reinflate to the maximum pressure on the tire side wall. Carefully inspect the tire for bulging, and discard it if you find any.

Personally, I would still be very wary of that tire and probably discard it. If I had no choice, I would run it on the back wheel where a sudden blowout is less likely to cause an accident (Risk of a blow out on the front wheel is almost certain, back wheel is highly probably).

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  • I once had a catastrophic tire failure where the bead separated from the rest of the tire. It sounded like a gunshot and was pretty exciting. The air pressure was much higher than 50 PSI. I got a free replacement tire from the manufacturer.
    – JimmyJames
    Sep 20 at 17:19
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If your inner tube didn't pop/rupture then it is fine to reuse.

Instead, your tyre's bead/hook failed to maintain its grab on the rim. Either it wasn't located right before you started inflating, or the hook is weak/damaged.

I would suggest you inspect the tyre and rim where they interface, and try reinstalling the tyre at a different rotation. If it still doesn't hold the rim, you might need a new tyre.

Remember the tube's only job is to hold air. The tyre's job is to restrain the tube.

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You probably pinched the tube between tyre and rim. If it still holds air there should be no permanent damage.

I’d deflate everything, then make sure the tyre is seated properly.

What I do after installing tyres (before inflation): Go around the rim, push the tyre bead+sidewall away from the rim along the whole circumference and check that you can’t see the tube. Repeat on the other side. Inflate to a low pressure and repeat the procedure. Then inflate to maximum pressure (or even slightly more) to check that nothing explodes. You might hear a few small “pop” sounds as the tyre bead settles. Release air and inflate to your desired pressure.

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I agree with the other answers that if the inner tube is still intact, it's fine to reuse. The inner tube holds the air in. The tire holds the inner tube.

A tire that bulges is damaged. Discard the tire now.

The strength members within the tire should hold its shape at any pressure. If it bulges, it means that some strength members, e.g., the tire cords, are broken - perhaps corroded, perhaps severed by something puncturing the tire. Increased strain will be put on the adjacent members which will be much more prone to failure. In the bulging section, all the strength is now being provided by the rubber, which will creep over time.

It's good that you witnessed the bulging when not riding. It's saved you from an unexpected blowout.

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