Method for controlling the footprint area of a tyre and tyre for vehicle wheels
A method for controlling the symmetry of the footprint area of a tire running on a straight trajectory with camber angle different from zero, includes the steps: reducing the contact pressure of the tire on the footprint area at an inner shoulder (in case of negative camber) or at an outer shoulder (in case of positive camber); and disposing any medium line of the tread band placed in correspondence with the footprint area substantially parallel to the ground. A tire and a wheel for motor-vehicles, wherein the medium line of the tread band and the rotation axis of the tire form an angle substantially equal in absolute value to the camber angle. A process for manufacturing such tires, wherein a green tire with symmetric outer profile is deformed during the vulcanizing and moulding step until a predetermined angle different from zero is formed between any medium line of the tread band and the rotation axis of the vulcanized tire.
1. A tyre for motor-vehicle wheels, comprising:
a carcass structure comprising a pair of beads having a same radial distance from a rotation axis of the tyre; and
a tread band disposed at a radially external position with respect to the carcass structure,
wherein the are symmetric relative to a mid-line plane of the tyre,
wherein, in each radial half-section of the tyre, the tread band is symmetric relative to a symmetry axis thereof,
wherein, in each radial half-section, a medium line of the tread band and the rotation axis of the tyre form a predetermined angle different from zero,
wherein a median circumferential line of the tread band is axially shifted by a predetermined distance between about 3 mm and about 30 mm relative to the mid-line plane of the tyre,
wherein axial end portions of the tread band have different axial distances from the mid-line plane of the tyre, and
wherein the axial end portion that is axially farthest from the mid-line plane of the tyre is also the axial end portion that is radially the farthest from the rotation axis.
2. The tyre as claimed in claim 1 , wherein said predetermined angle is greater than about 0.5°.
3. The tyre as claimed in claim 1 , wherein said predetermined angle is less than about 5°.
4. The tyre as claimed in claim 1 , comprising asymmetric sidewalls relative to a mid-line plane.
5. A motor-vehicle, comprising:
at least one wheel mounted with a predetermined camber angle different from zero,
wherein the wheel comprises a rim and a tyre mounted on the rim and inflated to an operating pressure,
wherein, in each radial half-section, a corresponding medium line of a tread band and a rotation axis of the tyre form a predetermined angle substantially equal to said predetermined camber angle, such that any medium line of the tread band placed in correspondence with a footprint area is substantially parallel to the ground, the predetermined angle being different from zero;
wherein the rim has housings for beads, the beads being symmetric to a mid-line plane of the wheel,
wherein, in a radial half-section of the tyre, the tread band is symmetric relative to a symmetry axis thereof,
wherein a median circumferential line of the tread band is axially shifted by a predetermined distance between about 3 mm and about 30 mm relative to, the mid-line plane of the wheel,
wherein axial end portions of the tread band have different axial distances from the mid-line plane of the wheel, and
wherein an axial end portion of the tread band that is axially farthest from the mid-line plane is also the axial end portion that is radially farthest from the rotation axis.
6. The motor-vehicle as claimed in claim 5 , wherein the camber angle is negative.
7. The motor-vehicle as claimed in claim 5 , wherein the camber angle is between about −0.5° and about −5°.
8. The motor-vehicle as claimed in claim 5 , wherein the median circumferential line is shifted toward an outside relative to the motor-vehicle.
9. The motor-vehicle as claimed in claim 5 , wherein the tyre has asymmetric sidewalls relative to the mid-line plane of the wheel.
10. A wheel for motor-vehicles, comprising:
a rim comprising two housings for beads having a same radial distance from a rotation axis of the wheel; and
a tyre mounted on the rim inflated to an operating pressure and comprising a tread band,
wherein, in each radial half-section of the wheel, the tread band is symmetric relative to a symmetry axis thereof, and
wherein, in each radial half-section, a medium line of the tread band and the rotation axis of the wheel form a predetermined angle different from zero,
wherein the beads are symmetric to a mid-line plane of the wheel,
wherein a median circumferential line, of the tread band is axially shifted by a predetermined distance between about 3 mm and about 30 mm relative to a mid-line plane of the wheel,
wherein axial end portions of the tread band have different axial distances from the mid-line plane of the wheel,
wherein the axial end portion of the tread band, that is axially farthest from the mid-line plane of the wheel is also the axial end portion that is radially farthest from the rotation axis.
11. The wheel as claimed in claim 10 , having asymmetric sidewalls relative to the mid-line plane of the wheel.