Ackermann steering geometry — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/ackermann/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Catalog version: 2026-10-20

Sizes: see table below
- Ackermann geometry turns the inside wheel more than the outside so both roll around one common centre without scrubbing (Wikipedia). The ideal condition is cot(outer) - cot(inner) = track / wheelbase (raw.org).
- A simple layout points the steering arms toward the centre of the rear axle so the tie rod and axle form a trapezium (Wikipedia).
- On RC cars more Ackermann gives sharper turn-in but can feel twitchy at speed and wears the inside front tyre (CompetitionX); Tekno adjusts it by moving the steering link fore or aft.
- The file is a reference example built by Xem Studio from the numbers above (Reference 1/10 touring car: wheelbase 260 mm (AARCMCC ISTC 250-270), track 190 mm (EFRA width without body), 50 mm = EFRA rim limit.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

parameter  value or range  source
Ackermann condition  cot(phi_o) - cot(phi_i) = w / l  raw.org
Inner wheel angle  phi_i = atan(2l sin phi / (2l cos phi - w sin phi))  raw.org
Steering-arm rule  arm pivots on line from kingpin to rear-axle centre  Wikipedia
Invented  Lankensperger 1816; Ackermann patent 1818  Wikipedia

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- raw.org (kinematics notes): Ackerman steering — web — Publisher's page; dimensions are facts — https://raw.org/book/kinematics/ackerman-steering/
- Wikipedia: Ackermann steering geometry — web — Publisher's page; dimensions are facts — https://en.wikipedia.org/wiki/Ackermann_steering_geometry
- CompetitionX: RC Ackermann Steering Explained — web — Publisher's page; dimensions are facts — https://www.competitionx.com/?p=14
- Tekno RC: Tekno RC Setup Guide — web — Publisher's page; dimensions are facts — https://teknoforums.com/misc/Tekno-RC-Setup-Guide.pdf

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/ackermann/index.json
API: https://xemstudio.com/api/geometry?object=ackermann