They seem to be so small and unstable, thinking about the weight of the airplane, especially filled with passangers and luggage. How do they carry the weight, as well as being able to accelerate and break and everything?
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Airplane wheels are huge and they have a lot of them. The look small compared to the size of the airplane. Airplane are compared to the volume lighter then cars or trucks.
Here is a human sitting on the wheels of a Boeing 747 [https://qph.cf2.quoracdn.net/main-qimg-9f2d76bc87612ad7b70333439ddac6e0-lq](https://qph.cf2.quoracdn.net/main-qimg-9f2d76bc87612ad7b70333439ddac6e0-lq) The tire is 49 inch in outer diameter and have 19 inch thread area.
A typical car has 15-19 inch diameter and an area around 9 inches wide. So a 747 tire is 2x as wide and 3x as tall but that is not the main difference
The bogie we see has 4 wheels and there are 4 of them in the rear so a total of 16 tires. Add to that the two in the front and you have 18 wheels.
The max takeoff weight is 412 tonnes for the freighter version. That means 26 tonnes per wheel.
The wheels are inflated to 205 PSI compared to around 30-40 that a regular car has. Trucks are around 115 to 130 PSI. This is the main difference between car and airplane tires 5-7x the pressure
The ground pressure of a tire will be very close to the pressure it is inflated too. 26 tonnes=57320 pounds 57320/205= 279 square inch contact area. It looks like the thread is 19 inches which means a distance of 279/19=~15 inches is in contact with the ground. If the pressure was the same as a car tire you need around 86-inch long contact area and it would require enormous tires.
So the answer is they are larger they just look small because airplanes are huge in volume. They have a lot of tires with high pressed and the resulting ground contact area get quite small. It is around 19 inches x 15 inches per tire for a Boeing 747
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