Staggered Vs. Non-Staggered Wheelsby Richard Rowe
Nothing speaks more or a vehicle's purpose, and the driver's priorities, than the tires it uses. A set of short-sidewall tires might tell passers-by that your car is a handler, and that nimble maneuvering is a top priority for you. Off-road tires say your life is in the weeds -- so to speak -- and a fat set of rear rollers say that you're either a straight-line speed demon or that you're putting loads of power to the ground. The practice of "tire staggering" can drastically alter both your car's performance balance and the message that its looks deliver, but approach with caution. These days, there's a bit more to think about than just looking cool and going fast.
What is Staggering?
Staggering is the practice of using different-sized tires on different wheels of the car on order to compensate for the different stresses that tires on the front and rear must deal with. A Top Fuel dragster would represent one really extreme case of staggering: its tiny pizza-cutter front wheels are absolutely dwarfed by the dragster's rear slicks. The Top Fueler uses extreme front-rear staggering like this because the rears are responsible for putting every one of those 10,000 nitro-powered ponies to the track, while the fronts wheels are only there to keep the nose off the ground and steer a bit.
Wider Rear Tires
Most of the time, you'll see tire staggering take the form of larger -- wider and/or taller -- rear tires. This big-rear-tire look is one that we've long come to associate with performance, and it is a necessity on some rear-drive cars. Wider rear tires mean more traction under acceleration, which is helpful when launching from a standstill, but can also be a life saver on the back roads. the best way to get through a corner is "slow in, fast out," meaning that you'll slow down to make the turn, turn in, hit the apex and "power out" of the corner after the apex. Applying the power in a rear-drive car while turning will almost always break the rear tires' traction and induce "oversteer" or "powersliding." While fantastic fun when intentional, and a good way to control the car's direction when used in moderation, an unwanted or unexpected powerslide is a dangerous animal. Big rear tires stabilize the back of the car, helping to keep it on track while turning. But you can definitely have too much of a good thing here; huge rear tires can create a car with terminal "understeer," meaning that it will always try to go straight instead of turn when you want it to.
Wider Front Tires
Wide rear tires look classically cool, but they're pointless on a lot of cars on the road today; the majority of front- and all-wheel-drive cars on the road today would probably do best with wider front tires. Front-drive vehicles always understeer when coming out of a turn, because you're forcing the front tires to both turn the car and put power to the ground. That's especially relevant when you consider that weight -- and thus traction -- shifts to the rear under acceleration, and to the front under braking. Wider front tires on a front-drive car will help it to do everything better: stop quicker, turn in sharper, hold the turn better and allow you to power out of the turn more viciously by warding off a certain amount of understeer. They'll also pay huge dividends in acceleration. Weight shifting to the back of the car at launch unloads the front tires, reducing grip and reducing the amount of power you can put down. Wider front tires can give you just the edge you need to go from a quick start to a neck-snapping launch. All-wheel-drive vehicles, which usually act like front drivers, can benefit similarly from wider front tires, albeit a bit less so.
Tire Diameter and Aspect Ratio
Taller tires, particularly on the back, do look cool -- but most of the time, the increase in diameter is a necessary evil, and a concession to the tire's aspect ratio. Aspect ratio is the height of the tire sidewall relative to its width; a higher number is a taller sidewall, and a lower number is a shorter sidewall, or "lower profile." If you increase a tire's width but not its height, you wind up with shorter sidewalls relative to the width, and an effectively lower aspect ratio. This is a vital consideration, because higher aspect ratios -- taller sidewalls relative to tread width -- provide more straight-line traction, but soften the turning response. Shorter sidewalls or lower profile tires provide sharper cornering response, at the cost of straight-line traction and smooth, predictable "break away" while cornering. So, if you install wider rear tires intending to increase rear traction and stabilize the car, but don't increase diameter, you'll wind up completely defeating the purpose. The lower rear aspect ratio will make the rear break away harder during cornering and lose traction faster under acceleration, making the car skittish and unpredictable while cornering.
There are a lot of practical considerations to bear in mind when deciding whether or not to go with a staggered tire arrangement. If you use different-sized tires on the front and rear, you can't rotate the tires front-to-rear, which is definitely going to cost you in the long run in terms of tire replacement. You can swap them side to side, but then you have to consider the type of tire. The best tires have directional tread grooves, angled backward to efficiently eliminate water. Directional tires can only turn in one direction, so in order to swap them side-to-side, you'll have to have them removed from the rims and re-mounted every time. That won't be cheap, fast or easy. And if you use super-high-performance "asymmetrical" tires that can only be used on the left or right sides of the car, you could very well wind up with four different tires that you can't rotate at all. That is a massive pain in the real world, so avoid it at all costs. If you run taller tires, you'll have to reprogram your car's antilock brake controller and drivetrain computer with the new tire size; otherwise, your antilock brakes, traction control, stability control and speedometer won't work correctly. Make sure your vehicle has the provisions to reprogram these controllers before you buy the tires. You can't use different-height tires on all- or four-wheel-drive vehicles.
The Right Size, the Right Stance
At the end of the day, tire staggering is all about changing the car's traction balance under cornering, braking and acceleration. That change in traction balance comes by way of different tire widths, so that's where you'll want to start when deciding on a stagger. First, pick the width ratio that will give you the change in traction balance you're looking for. If you need a bit more traction in the back, use rear tires that are 10 to 20 percent wider than the fronts -- or use whatever percentage suits your needs. Vice-versa for the fronts. Once you have the width selected, make sure you can reprogram your car's computers to accept taller-diameter tires on the front and rear axles separately. Once you've confirmed that, you need to decide on an aspect ratio. In general, you're going to find the best performance balance, and the coolest visual "stance" by using the same aspect ratio front and rear. On a rear-drive car, that means slightly shorter, thinner tires on the front and taller, wider tires on the rear. That'll give you a very cool "rake," or downward-pointed nose, good for both performance and show points. If you must use different aspect ratios, try to put the lower-profile tires on the non-driven wheels; that may require a larger diameter rim on the non-driven wheels if you want to maintain a certain tire height.
- Chassis Engineering; Herb Adams; 1992
- Race Car Engineering and Mechanics; Paul Van Valkenburgh; 2001 Edition
Richard Rowe has been writing professionally since 2007, specializing in automotive topics. He has worked as a tractor-trailer driver and mechanic, a rigger at a fire engine factory and as a race-car driver and builder. Rowe studied engineering, philosophy and American literature at Central Florida Community College.