Tire popping off rim

[Nuffy]

I was riding the skate park in George last weekend and my back tire just popped one side completely off the rim (while riding on the flat). The tube bulged out, but thankfully didn't burst. I put it all back again, and rode a bit more. Then in the car on the way home the same thing happened again.

 

I had been riding the George downhill before hand without any problems, and it's never happened to me before. I'm using a Mavic EX721 rim with a Michelin Comp 16 tire (I think - it's the Michelin 2,3 inch version of the Highroller), both in good condition. The only explanation I can think of is that I had been using the same tube with a much larger diameter WTB 2,4 inch Motoraptor tire, and it seems to have stretched. It looked a little too big for the Michelin tire. But could that really be the problem? I checked and checked again that the tire was properly seated, so I'm confidant that I didn't just fit it wrong.

 

Any thoughts?

 

[Dirtbreath]

What pressure you running at? Might be too low?

[Nuffy]

I'm not sure of the numbers, but I run mine pretty hard. I weigh about 85kg and like to be sure I don't pinch flat.

[Johan Bornman]

It has nothing to do with the tube - that I know.

It is purely a function of the pressure in the tube/tyre and the tyre's capacity to resist that pressure.

 

Wider tyres can handle less pressure than narrower ones. The reason for this is simple. A wider/bigger tyre has more surface area and each unit of surface area (every square inch say) can only take X pressure. If you have more surface area you have more overall pressure in the tyre and the bead lifts up and allows the tube to escape - a little bit like a hernia.

 

My guess is that you exceeded the tyre's maximum pressure.  Double check that and then report back to us.

 

You can also see if the tyre is defective by doing the following.

 

1) Lock the dog up in the bedroom with some loud music.

 

2) Put on safety glasses and ear protectors.

 

3) Pump the hell out of the tyre and keep a watch on the pressure gauge. Memorise the last reading just as the garage windows blow out from burst tube.