"Increasing wheel diameter one inch -- or one plus size -- offers the greatest benefit in overall performance" when plus-sizing tire and wheel packages, according to a study in the January 2004 issue of Consumer Reports.
"After that, you're likely to pay for small gains in grip and handling with big losses in ride comfort, hydroplaning resistance and snow traction," says Eugene Peterson, the magazine's senior automotive and tire test engineer.
Consumer Reports recently evaluated Plus One, Plus Two and Plus Three tire and wheel packages at its East Haddam, Conn., test facility.
"Plus One is best for those who want better handling and cornering without losing much foul-weather grip. But ride still suffers, and costs for wheels and tires are significant even at this level."
Consumer Reports declared Plus Two "best for those who value style and dry-weather grip over all-weather performance," but fitments in this range are susceptible to damage from potholes and curbs.
"Plus Three are best for warm-weather drivers who want even more style and are willing to pay for it. But you'll need to be especially careful (driving) through puddles; potholes and curbs pose added risks."
In addition, Consumer Reports does not recommend plus sizing for SUVs.
"Larger, grippier tires could make some of these (vehicles) tippier by sticking rather than sliding under hard cornering forces and also during emergency road maneuvers.
"Extreme plus size truck tires put an even greater strain on brakes, wheel bearings and suspension parts."
