Heavy-pickup drivers often do what truckers do, running a traction tire on the drive axle and a highway tire on the front steer axle. This often works on 4WD versions as well, because aggressive traction tires tend to wear out quickly on heavily loaded steer axles. Also remember that a camper added to any independent front-suspension pickup will probably affect front-wheel alignment, and a highway ribbed tire will put up with misalignment a little better than a traction tire.

If you're being honest and are pavement-bound for most of the year, a street-oriented tire is your best bet. Many manufacturers are building tires "designed for SUVs" these days, so the choice arena is large. You can also opt for a "Plus" conversion for higher performance at some sacrifice.

Ford's Harley-Davidson F-150 comes with a Plus conversion built in, with 20-in. wheels right from the factory. BMW's X5 V-8 offers an optional sport package that includes 18-in. wheels in front and 19s in back. These are all low-profile tires designed for performance pavement use, regardless of what it says on the sidewall.

A Plus conversion uses a larger wheel (plus X number of inches over stock diameter) and lower-profile tire to give better street performance from the same height tire: for example, the 255/65HR16 on a recent Range Rover 4.0SE becomes a 255/55HR18 like that used on the 4.6HSE. This example uses the same width tire, but you can also increase width (as clearance allows) so you might go from 255/65HR16 to 285/50HR18. Toyo goes out to 23-in. tires for its performance Proxes line and recently introduced a 33x13.0R18 all-terrain for those who want a flotation tire on a large-diameter wheel.

A lower-profile tire sharpens steering and braking, is often stickier and has more grip, and usually detracts slightly from ride quality and adds to road noise. Low-profile tires must be used with caution off-road for three reasons: one, lowering air pressure if you get stuck doesn't enlarge the contact patch as well as it does on standard tires; two, the wheel is closer to the ground so it's easier for small pebbles, sand, or other debris to get lodged in the bead, which will eventually cause an air leak, damage the bead, or both; and three, there's less sidewall and flexibility to wrap the tire around rocks, roots, or downed branches for traction.

If you decide to change tire size in any fashion, be cognizant of downstream considerations. Larger tires, even if they don't run afoul of bodywork, may stick out to the point they're illegal. Bigger generally means heavier, with more stress on wheel bearings, ball joints, steering pumps, and so forth, and heavier rotating mass means longer stops. Finally, taller tires will change gearing and speedo/odo readings, and if the change is more than about 10 percent, driveline inputs to stability and anti-lock systems will be affected and those systems function differently or not at all.

When changing tires and/or wheels, get five (or seven for dualies) if at all possible. This should be a requirement for 4WD, because, by definition, 4WD wants to drive all wheels the same, so having different sizes will defeat the purpose. Remember that regular maintenance (pressure, alignment, lug-nut torque, cleaning) will affect tire life as much, or more than, your driving style.