The only way a diameter might effect wheel acceleration is that weight further from the center is harder to rotate than weight closer. 50mm has weight further from center than 30mm naturally. On the other hand 50mm is stronger, therefore thinner, so maybe lighter. If so it may rotate slower, or faster for the same force applied. It would depend on the weight of each. I think the difference will be very small.
As for the wheel, it goes around once every time the axle does. As for the axle it goes around at a ratio relative to the clutch base on the sprocket ratio.
One scenario I can think of that might throw people off… When people change the axle it’s a handling decision… Without a differential a kart will scrub/bind in turns unless you unload the inside rear wheel. Axle choice (Along with other factors) influences how and when the inside rear wheel unloads and reloads while cornering.
Can you explain what you mean by unloading the tires mean. Does this have to do with air pressure, or castor and camber.
Can you believe I’m writing all this down. I want to make sure I understand everything we are talking about here because this is some good info. I’m learning something here. I want to thank all you guys who responded to the topic. I’m getting some good info.
In a sense, a kart is a very fast tricycle. Because you have a solid rear axle, basically a fully locked differential the rear wheels scrub as they fight each other making the kart push and/or scrub off speed.
So what we do is tune the kart to unload the inside rear wheels of a turn. Controlling when and how much it lifts/unloads is the fun part of timing.