Photo by Simiant/Flickr.

“While in 1983 a pothole would need to be over 3 inches in depth and over 30 inches in
length to pose a rim damage threat to even a mini-compact vehicle, in 2006 holes as shallow as
1½ inches no more than 16 inches long could, in theory, cause rim damage.”

That’s from Influence of Road Surface Discontinuities on Safety: State of the Art Report, a new TRB circular.

The reason is “plus-size tire rims,” a form of road social signaling that basically says, “I’ve got money to spare on rims” that will soon need to be replaced.

“The principal disadvantages [of plus-size rims] are many and include cost, weight, fuel economy, ride quality and wet grip/snow traction, as well as indicate hydroplaning resistance. Perhaps more serious downsides include reduced load-carrying capacity at extremely low aspect ratio, a shift in the handling balance toward oversteer and a slight increase in rollover propensity. A further disadvantage is that the increased vertical stiffness of low aspect ratio tires means they act as shock transmitters rather than shock absorbers. Safety implications arise when a motorist will agree to replace a bent wheel that is no longer able to hold air, but will continue to use an injured tire since the damage is internal and not visible to the naked eye.” (Walter, J. Style Over Substance. Tire Technology International, March 2006.)

The authors also conclude, by the way, that potholes have little negative effect on road safety.

And one last thing: The vehicle brand above is now the property of an obscure Chinese company. Will they still be adorned with all those ultra-patriotic bumper stickers?

This entry was posted on Tuesday, June 2nd, 2009 at 4:53 pm and is filed under Traffic Wonkery. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.