The custom wheel market has become a multibillion-dollar business, fueled by the growing practice of installing supersized, often chrome- bedecked wheels on cars, trucks and SUVs.

So large and ornate, a set of four -- plus the tires -- can cost nearly $20,000. But the stylish swagger afforded by these accessories also compromises driving safety, vehicle maintenance and ride comfort.

Installing large wheels without accounting for the potential effects on a vehicle's performance limits can exaggerate the risk of hydroplaning or cause brakes, shocks and springs to wear out more rapidly than usual, experts say.

Consumers are often blinded to these issues by the bling-bling.

"A lot our clients, they don't care," said Ryan Friedlinghaus, whose California-based company, West Coast Customs, partners with Detroit-born rapper Xzibit on the MTV vehicle makeover show, "Pimp My Ride." "They just want the biggest and best that's out there."

Automakers and parts suppliers are responding with aftermarket brake system upgrades and a high-pressure approach to education.

The term "plus-size" refers to a wheel diameter increase of one size, from 16 inches to 17 inches, for example. Plus-two is an increase of two sizes, and so on. The term "dubs" has caught on as the shorthand for 20-inch wheel rims.

Consumer Reports, which only recently began testing the larger wheels, recommends that vehicle owners stick with a manufacturer's wheel specifications. But if the allure of chrome is overwhelming, the popular shopping guide suggests moving up to plus-two, and no more.

Plus-size wheels offer some benefits in driving dynamics, according to Eugene Petersen, Consumer Reports' tire testing program manager.

"We saw some slight, minor improvements in braking distances," Petersen said. "We also saw better emergency handling."

The latter finding is a function of the low-profile tires with which plus-size wheels must be fitted. As wheel size increases -- sometimes up to 28 inches -- tire height from rim to tread must decrease so their combined diameters do not exceed the space available in a vehicle's wheel well.

The crisper response observed by Consumer Reports occurs essentially because there is less rubber through which steering inputs must be transmitted. But bigger is not always better, Petersen warned.