Unlike a square tyre setup in which all tyres are of the same dimensions, staggered tyre setup is one in which the front and back tyres are different in size with bigger rear tyres and smaller front tyres.
It should also be noted that staggered setup does not apply to just wheel width. Some cars may also have different wheel diameters in the rear and the front. These are more common in F1 and sports cars. The difference in front and rear wheel size enhances the look of the vehicle and makes the vehicle look more aggressive.
So, which tyre setup is better? That depends on an extensive variety of factors: the vehicle, personal driving preference, driving style, and intended purpose. Here are pros and cons of staggered tyre setup.
A square tyre setup produces more front-end grip when cornering and leads to greater high-speed stability as the front end of the car feels more “planted” because of the greater contact area. Also, the ability to swap front and rear tyres, and vice-versa based upon rate of wearing down, is a huge practical and economic advantage.
Besides providing a more commanding look and better performance because of enhanced road grip when outfitted with larger (or wider) tyres in the rear, there are a few more advantages worth noting. Some vehicles have the dominant part of their weight over a single axle. If so, it is better to have bigger wheels in the back than the front, if majority of weight is in the back. Note this wouldn't generally apply if the vehicle had the dominant part of its weight in the front, as vehicles should always stagger from back to front.
Staggered tyre setup can also improve vehicle stability, particularly with regards to performance vehicles that you don't want veering from side to side when you put the pedal to the metal. Furthermore, staggered wheels additionally allow more responsive braking and better cornering.
Staggered tyre setup is most commonly used in performance vehicles like Chevy Corvette, Ford Mustang, BMW M3, Mercedes-AMG, Porsche 911, and so on. In these vehicle applications, staggered tyre setup is chosen to enhance performance and specific handling requirements.
As with any change to a vehicle, if you change it an excessive amount you can affect your vehicle negatively. If you go too wide the tyres can wear unevenly. Tyres that are too wide for the wheels will in general rub against the tread making them wear exorbitantly in the centre. Going too wide can likewise cause clearance issues. The tyres can end up rubbing on the bumper wells and on suspension segments causing damage. Tyres that are too wide will likewise lead to unreasonable load on the hub bearing which will make them wear rapidly.
Another negative impact that the staggered setup has on is fuel mileage. Introducing wider tyres means more tyre contact with the road. Excessive contact causes excessive friction making it harder for the motor to get the vehicle moving. This additional load can decrease your fuel mileage by as much as 20%.
In conclusion, there is no "right answer" to the subject of Staggered versus Square tyre setup. It boils down to individual inclination, and by and large there is merit to both. Still, it's more typical for drivers to swap from a staggered to a square tyre setup, both to change vehicle handling and performance, and to enhance tyre wear and life.