Originally Posted by RogerDaShrubber
All rubber tires balloon, even those 1/8th belted ones you linked, watch them in slow motion and measure the deformation cause by inertia. They might not grow to 4 times their size like an offroad tire will, but, even 1mm is still the tire ballooning. The only tires that do not deform from inertia are foams and any other solid material that cannot stretch.
Foam tires do the same thing, sorry say.
Foam inherently is a elastic material.
I have a set of foams and a set of those Sweep belted tires - they both slightly expand about the same amount under load.