If 2 identical vehicles were accelerating on dry pavement, one with standard tires and the other with oversized tires, would it take the same amount of time for both vehicles to stop?
by 
Anonymous
ANSWERS: 4
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Your question asks about both acceleration and stopping, so I'm not sure which you really meant, but both are essentially the same thing, so I can answer both simultaneously. In theory, the tire which is placing more rubber into contact with the pavement will have more friction, and thus would be able to make use of greater acceleration or deceleration force, thus resuslting faster acceleration or braking. Thus the large "slicks" on dragsters. You asked about dry pavement, and implied straight line. A tire which must also be able to corner competently, and accomodate varying surface textures and conditions, such as wet or icy, must of course make compromises to that dry straightaway ideal.
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I disagree with the previous answer. You do tend to need more rubber to allow for more HP or weight, true, particularly in large-scale applications (heavy loads, drag racers, etc). However, literally speaking, the force applied by 1 lb to a 1 sq-inch area or a 2 sq-inch area is the same; except in the 1 sq-inch case, there is twice as much force per square inch. The smaller contact patch provides just as much force pressure as the larger one, it's just that the larger once can handle more variation in surface, because it's covering more surface. My '76 Mini Cooper will accelerate faster with smaller tires, and brake more quickly as well, because of a simple matter of mass: smaller tires weigh less, and require less effort for the motor to turn them. There is also a small gearing difference; shorter tires make better use of engine power at low speeds/rpms, taller tires at high speeds/rpms.
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If by "oversized" you mean a larger diameter then your braking distance would, if anything, increase. The contact patch would be further from the axle thus having more leverage to counter the force of the brakes. If by "oversized" you mean wider then your braking distance will likely decrease. Most vehicles are capable of locking the wheels up so your braking distance is usually more dependent on your tires ability to grip the pavement than most people think. Putting too much pressure on the ground will overload the tires and you'll wind up floating on a thin layer of molten rubber; it's called "skidding". More contact area will reduce the pressure by putting the same force over a wider area. Additionally, the increased contact area will usually increase rolling resistance thus slowing the vehicle further.
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Depends on the weight & traction between the two.
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