Marty -
TORQUE is what is being put to the ground for acceleration... more contact patch is going to "hook up" faster. Just look at the 10.5 tire guys on the drag strip. They're putting down big numbers with what is really a pretty "skinny" tire. But they've mastered weigh transfer... the track is gooey... and so is the tire. Put a 200 tread wear 345 wide tire on the car and it'd probably smoke 'em all the way down the 1/4 mile!
WEIGHT coupled with VELOCITY are the load forces that a Track Car is going to see in a corner - HP and TQ then really don't come into play except that the more TQ and HP a given vehicle has will obviously determine the velocity. The Mustang runs 245 X 45 Z 16's -- Hoosier R6's... they'll actually turn to liquid and stick like frigging glue once you get some temps up in 'em. Cold - they suck!
The tread wear # probably has as much to do with both of the above as does the width (contact patch). So a guy could run a skinnier tire and run 200 TW and corner and accelerate as well or better than a wider tire at 400 TW. So depending on "USE" -- the width is more about looks than actual tire loads and traction.
The part I laugh at the most is the size of the brakes on STREET CARS... because if the car doesn't have ABS -- then the most braking the car can do is whatever the TIRE / Contact patch is capable of. 6 piston Brembos - locked up are probably every bit as good as a single piston PBR.... if they're locked up and you're skidding it doesn't matter how "big" they are.
The bigger rotor and brake is about how much HEAT they can absorb and continue to function properly. On a street car - how much heat are they going to have to absorb?
So --- What Vince said is really the determining factor -- and it's all about KOOL and what looks good.... big azz tires and big azz brakes just look kool!
I was told -- because I haven't experienced it yet - that the Miatas will just run away from you on a track. They don't have to hit the brakes -- and don't have much torque or horsepower... so mat the gas and hit terminal velocity and never slow down.... "US" with bigger HP and TQ are hard on the throttle and then we scrub all that speed OFF to make the corner... Having said that - I'd prefer my Mustang and it's 590 HP motor over the Miata (yes I owned one - great little car) any day.
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