Many drivers believe that, whenever tires should be rotated or replaced, it is better to install them with a different degree of wear at the front and at the rare. It has become a common practice that a new couple of tires, or the ones with more tread, are installed at the rear, while tires with the least tread are put at the front. This practice is bolstered by the opinion that installation of differently worn tires at the front and at the rare ensures a better “safety net” of understeer for a driver, so that the car skids before it spins. For the same reason, many of passenger vehicles are designed with a little of negative camber at the rare wheels, which provides an additional safety measure. However, is it really necessary to put the least worn tires at the rare? And does the drivetrain layout – fwd, rwd, etc. – make a difference for rolling traction?
Actually, placing the most deeply treaded tires on the rare axle maximizes rare axle traction in the wet, when both loss of traction and car control is most likely to occur. The basic rolling traction does not depend on drivetrain layout, so, rear-, front-, or 4-wheel drive really does not matter much.
However, while the practice of installing tires with different traction at the front and at the rare might be justified in wet weather, in dry weather it is different. On a dry road, a well-worn tire can have more traction than a new, fully treaded replacement. And, if the worn tire is put on the front axle, this may reduce understeer and promote oversteer – but only if you drive on a dry road.
In view of the above and taking into consideration that, in your real driver’s life, you will inevitably have both wet and dry days, it is the best to keep all four tires in approximately similar condition, and of course well-treaded tires are always better than “bold” ones. This will inure that the stability of your vehicle is well preserved, right in accordance with the car’s designed handling balance.