Tire ballooning is when the tires spin so fast that the air inside gets hot & expands the tire size!

As owner of several RC models from 1/36th to 1/5th scale I'm pretty sure tyre ballooning is caused by centrifugal force, not air expansion.

I doubt this would happen with LEGO tires, because there is no real tire pressure, nor is there an airtight seal between the wheel and tire.

I doubt this would happen with LEGO tires, because there is no real tire pressure, nor is there an airtight seal between the wheel and tire.

There is no extra pressure in RC tyres. Unless you glue them there isn't usually an airtight seal either. The main reason this wouldn't happen with lego is that all the lego wheels I have are solid rubber. RC tyres are hollow like a car tyre and rely on foam inserts to provide the cushioning. This means they are more flexible and deform much more easily.

A foam insert taped to reduce ballooning.

Only moderately effective :)

Most Technic wheels should be able to suffer from the same effect, if you got it spinning fast enough. And I agree that it is the centrifugal force and not air expansion that's the cause. If it was air expansion it would balloon rather than becoming a disc... You can also see that the tire detached from the rim, and I doubt there's a hose in there...

Also, the LEGO tire would fall off way before it would balloon, on an RC car, the tires are either beadlocked on offroaders, or glued on road cars or both, my 1/10 Tamiya onroad car with a brushless motor had unglued tires on before and would just whip them off before it even got to top speed.

And Ballooning is caused by shear speed of the tire, not air. New RC cars today can easily get up to 70 mph, any tire at that speed will deform without any support inside the tire.

A Technic tire could stay in place, the rim is narrower in the middle with flanges on the sides. So it is possible it stays put even in ridiculous speeds.

70 mph is ~112 km/h. Let's say the tire has an diameter of 70 mm (before starting to expand), that's an circumference of 70 x pi = ~220 mm. To travel 112 km it needs to make 112 000 / 0,22 = ~510 000 revolutions. To do this in 60 minutes it needs to rotate at 510 000 / 60 = ~8 500 rpm.

I'm pretty sure I don't want to stand next to a LEGO wheel attached to a technic axle at that speed... But this is crazy enough that I might have to do some testing.

This is actually possible with Lego!

I am not near my collection so I can not show it to you, but with the necessary parts anyone can have a go with it.

I did all sorts of experiments in the past with wheels and motors, and was amazed by this "ballooning"

You need a wheel from set 8880 connected directly (with an axle of course but no gearing) to this 9v motor, connect a powersource and away you go!

Don't expect the tire to come off, the effect is less wonderful than that, but the centrifugal force will create a small gap between the rubber and the rim.

This is very well replicable in Lego with + + .

There is a YT video showing LEGO tire expanding and spinning of the wheel. The whole setup is, of course, LEGO.

I cant find it right now...

That old motor is at 2 000 rpm...