Here's a brief summary of some alternative tire concepts from various tire manufacturers over the years:
* Michelin PAX-Unveiled in early 1997 and originally dubbed PAV (for pneumatique accrochage verticale, or vertically anchored tire), PAX is a tire/wheel concept with vertically anchored beads in a specially designed flat platform wheel and an elastomeric insert providing both bead locking and run-flat support functions.
PAX is now commercialized and original equipment on a growing list of cars, including the 2005 Honda Odyssey van and the Audi A8, A6 and A4 models.
* Continental CTS (ContiTireSystem)-This tire/wheel concept, unveiled in the mid-1980s, featured inverted beads that wrapped around the edge of the flat platform wheel and were anchored in place by a locking ring. It offered extended mobility, but never gained widespread acceptance beyond a few special fitments on armored and other emergency-type vehicles.
* Michelin TRX-A tire/wheel combination, TRX featured a flatter bead angle, and hence a special wheel, for enhanced lateral handling. It achieved relative success as an OE fitment in Europe during the 1980s.
* Pirelli DIP-A zero-pressure tire from the early 1970s, DIP featured concave sidewalls and a special narrow rim with locking beads. It never went beyond concept.
* Dunlop Denovo-A run-flat tire/wheel concept from the early 1970s, Denovo required a special rim and had containers inside that provided a lubricant if the tire lost pressure. It gained limited optional OE fitment in Europe.