In our test of summer and all-season ultra-high-performance tires, we identified a few excellent tires from Falken, Michelin, Nitto, and Pirelli and found big differences in performance among models in the group.

These tires, also called UHP, are designed to offer tenacious grip and superior handling. Once found only on high-end sports cars, they are now on a wider variety of cars, including sports sedans and more-affordable sports cars, such as the Mazdaspeed3 and Saturn Sky.

UHP tires are Z-rated, meaning that they're capable of sustained speeds of 150 mph or more, and they often come in wheel diameters of 17 inches and up. As a trade-off for grip and handling, these high-end tires might be hard-riding and quick-wearing. The summer tires are useless on snow or ice.

We tested 21 sets of summer UHP tires and 15 sets of all-season UHP tires. Prices for both types ranged from $80 to more than $200 apiece for the 225/40ZR18 size we tested. Most summer UHP tires handled the important challenges on wet and dry roads very well. The all-season UHP gave up a little performance in return for better capabilities in wintry conditions. We found wide variations among the different performance categories, such as handling, braking, and noise, so there's plenty of room for the consumer to choose a tire tailored to individual preferences.


A NEW TEST FOR TIRES

This year we ran a new wet-pavement test geared toward UHP tires. We created a handling course through closely spaced highway cones and wetted the pavement so the surface was slick. Then different drivers took turns pushing our Audi A3 3.2 test vehicle to its limits through the course on each set of tires.

We combined those results with our standard wet-cornering test, in which we drive at ever-increasing speeds around a circle of wet pavement, noting a tire model's peak lateral grip.

We hired a contract laboratory in Texas to conduct tread-wear testing for us on the government's tread-wear course, which is a road circuit designed to mimic both city and highway driving. We measured tread loss up to 12,000 miles of use. That lets us compare relative tread life from one set of tires to another.

Historically, tread life has been a low priority for UHP tires, and many don't carry tread-wear warranties. Most UHP tires still wear more quickly than lower-speed-rated counterparts. We found that wear varied from model to model and is worthy of consideration when considering which of two similar models to buy.