Heavy steel wheels are relatively rare in showrooms these days -- it seems they are heading the way of bias-ply tires. Most new cars are delivered with cast aluminum wheels. While cast wheels weigh less than comparative steel wheels, they are still manufactured with thick castings and solid spokes (forged aluminum wheels, both lighter and stronger, are generally more expensive and as such, fitted largely to performance vehicles).
It's been well over a year since Michelin unveiled its take on the future of the tire, the airless Tweel. The odd-looking invention pairs a replaceable outer rubber layer with a central alloy hub joined by polyurethane ribs. Judging by this video, it would appear that the tire manufacturer is continuing to develop its concept, testing it on a variety of vehicles in a number of different environments. Click on the link to get a glimpse of what might just be in your automotive future.