Scrub radius — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/scrub-radius/  (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
- Scrub radius is the front-view distance at the ground between the steering axis and the contact-patch centre (Wikipedia). Positive scrub lowers parking effort and adds road feel; negative scrub resists pull under uneven braking or a flat tyre and reduces torque steer.
- Zero scrub causes the tyre to 'squirm', wearing it and reducing stability (Wikipedia; H&R). A small radius improves steering feel; a large one increases torque steer (HPA).
- Wheel offset is the easiest way to change it; more aggressive offset increases scrub radius (HPA; H&R).
- 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
Older cars  about 100 mm (4 in) positive  Wikipedia
MacPherson strut  usually negative  Wikipedia
SLA double wishbone  usually positive  Wikipedia
FSAE example  27.768 mm front, 56.529 mm rear  Univ. of Utah FSAE

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Scrub radius — web — Publisher's page; dimensions are facts — https://en.wikipedia.org/wiki/Scrub_radius
- H&R Springs (Roger Jackman): Scrub radius — web — Publisher's page; dimensions are facts — https://hrsprings.com/technical/scrub-radius
- High Performance Academy: Wheel alignment terminology: king pin inclination and scrub radius — web — Publisher's page; dimensions are facts — https://www.hpacademy.com/courses/motorsport-wheel-alignment-fundamentals/wheel-alignment-terminology-king-pin-inclination-and-scrub-radius
- University of Utah, Mechanical Engineering: Formula SAE Suspension System (senior design) — web — Publisher's page; dimensions are facts — https://mech.utah.edu/wp-content/uploads/2024/12/5-Formula-SAE-Suspension.pdf

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