Wheel rise, eventually, to classical Greece after the breaking of Minoan dominance and consolidations led by pre-classical Sparta and Athens. Celtic chariots introduced an iron rim around the wheel in the 1st millennium BCE. The spoked wheel was in continued use without major modification until the 1870s, when wire-spoked wheels and pneumatic tires were invented. The wire spokes are under tension, not compression, making it possible for the wheel to be both stiff and light. Early radially-spoked wire wheels gave rise to tangentially-spoked wire wheels, which were widely used on cars into the late 20th century. Cast alloy wheels are now
Rim (wheel) object. Some authors are careful to use "rim" for only the outer portion of a wheel, where the tire mounts, just as the rim of a coffee cup or a meteor crater does not refer to the entire object. One engineering text says "alloy wheels [are] often incorrectly called aluminum rims". Others use "rim" to mean the entire metal part to which the tire mounts, because the rim and the wheel are often cast or stamped from a single piece of metal instead of being distinct as with wire wheels. At the same time, "wheel" may refer to the entire