It seems to be a common theme on YouTube and some other places that ballooning tires = fast. Is this necessarily true? I feel like it just means air is entering from a bad glue job. Let me know what you guys think

Tire ballooning is bad for racing and is something to be avoided. Mostly happens when accelerating and the center diff is very light and basically the front diffs out. Pretty much means you won't have much steering when accelerating and the wear on the tire will be awful.
If you're talking about all four wheel ballooning when accelerating it's just the motor which is OP. Way too much power for anything to be controllable. Again tire wear, suspension compromised (foam won't do it's job )etc...

Has nothing to do with how tires are glued. Has to do with the effects of centrifugal force.

I installed a 7.5t sonic m3 in my b4. The tires are only ballooning slightly. Is that normal?

Should a 7.5t sonic motor make my b4 tires balloon?

They'll stretch out a bit on the straight away but they shouldn't necessarily balloon like what you see in overpowered setups.

Okay cool. I've yet to even try it out on the track. I'm just skeptical about how it all soldered together lol

Ballooning tires are basically a variable speed transmission and they work on rc cars the same as they do on drag cars. You don't want them to balloon to the point the blow apart or instantly at the hit of the throttle but you do want them to balloon some on the straight away to give you that little extra speed.

Tires will balloon. Now, If they balloon while you are racing, that's not good. Means lack of traction or car is over powered or over-geared. Wheel spin which created ballooning of the tires just gonna get you nowhere fast while overheating the motor, wearing the tires and draining the battery. In the basher truck I used to put duck tape inside the tires and in my racing cars just poke a hole on either the wheels or the tire so that the tire comes back to normal shape if it happens to balloon.

It also depends on the tires being used. Big, wide, soft MT tires will balloon much more than most other tires. Just because of size and softness.

It is strangely satisfying to see a tire balloon to the point it separates from the wheel and continues rolling for ages lol.

I'm surprised my Ten-MT tires are still glued to the rim with factory glue. Those tires on 3s balloon so large you can't make turns on the throttle. The tires rub against the body bad when you turn. The grow like 2-3 times in diameter at full throttle.