A: When a tire is orientated at an angle not equal to its direction of motion, a side force acts perpendicular to the plane of the wheel. The relation is nearly linear for small slip angles. The relationship that defines side force as a function of slip angle makes use of the tire cornering stiffness.
The SAE book by Gillespie, Fundamentals of Vehicle Dynamics p 347-355, indicates that
- for bias-ply tires cornering stiffnesses are approx 12 % of the load on the tire (with a range of approx. 8%-18%) and
- radial tires cornering stiffnesses are approximately 15% of the load on the tire (with a range of approx. 11%-19%).
- There are also discussions in the book about the effects of inflation pressure
- (normally increasing the inflation pressure increases the cornering stiffness),
- tire size and width
- (larger size and width normally produces greater cornering stiffnesses),
- tread design and aspect-ratio
- (aspect-ratio=ratio of section height to section width, common vehicles ranged from 0.78 to 0.70,
- recent trends towards lower-aspect-ratio performance tires (0.60 and lower) on cars may produce cornering coefficients in the range of as much as 25% to 30% of the load on the tire).
For additional discussion please see the msmac input manual discussion:
- Here’s a link to the online version:
- Discussion: Cornering Stiffness (use login: mchenry password: thankyou!)