# How do aircraft tyres straighten themselves when landing in a crosswind?

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How do aircraft tyres straighten themselves when landing in a crosswind?

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If the side slip (edited) is executed correctly, the wheels shouldn’t have to straighten, the ground track should be straight.

The upwind wheel should touch first, going straight, then the downwind wheel. There should be no side load on the wheels.

I might have misunderstood your question??

I’m fairly certain that they are built off centre. Similar to how office chair wheels are designed.

So the drag of the air, and then the tarmac will cause the wheel to align with the direction the plane is landing

When the aircraft is airborne in a cross wind, the plane is facing slightly off it’s travelled path so the the sum of forces acting on the plane pushes it in the direction it wants to go (Thrust from the engines, wind, push from control surfaces – ailerons, rudder etc). Once the plane touches the ground, the drag force from the rolling resistance one the wheels and braking once engaged starts to dominate. The wheels are much more able to resist lateral forces from the wind as they can act on the ground whereas the plane in the air has nothing to push against but you still have to control the plane to keep it from being pushed around.

All that said, the wheels don’t really push the plane to straight – the pilot uses the control surfaces to straighten the plane (I never finished learning to fly but [this page](https://www.boldmethod.com/learn-to-fly/maneuvers/how-to-make-a-perfect-crosswind-landing-every-time-touchdown/) goes over some of the ways you can land in a cross wind in fairly simple terms)

A pilot will apply rudder just before touching down, to ensure the wheels are pointed down the runway. An aircraft shouldn’t land in a sideslip.

For crosswind generally an aircraft can perform the approach (potentially all the way to landing) in two basic ways:

* Using a sideslip. The aircraft “dips” one wing towards the wind to offset the crosswind. Using this technique the aircraft wheels remain aligned with the runway and there are minimal side forces.
* Using a crab angle. The aircraft is turned sideways into the wind. If maintained until touch down, there will be some side forces on the landing gears. However, on large aircraft, the landing gears are engineered to withstand the side forces during crosswind landings.

Often pilots will land with a combination of sideslip and crab angle. E.g., use a crab angle during an approach but partially or completely de-crab (potentially with some sideslip) during flare and subsequent touchdown.

If fully landing on a crab, airplane will naturally straighten itself due to momentum and forces on the landing gear the. The pilot also provides control inputs (rudder & aileron) to control the direction of travel.

Note: sideslip is limited during landing due to wing clearance from the ground. Crab angle is usually limited by the amount of crosswind and the condition of the runway.

For small, high-wing planes like Cessnas, sideslip is probably the preferred method. The high-wing gives plenty of sideslip angle to work with and the landing gears on small planes don’t take well to a lot of side forces.

On the opposite spectrum, some very large aircraft have [main gears that can be steered / swiveled](https://www.youtube.com/watch?v=nhVD3E0-0Wc)so they can land crabbed even in very high crosswind conditions.