18 or 20" wheels?
#21
Norm
#23
I have 19 all around but if I could do it again, is probably keep the 19s in the front on my 245s and then go 20s in the rear with like 285s. That's how the gt500 comes stock anyways.
#25
There is no obvious need to have 6" wheel to rotor difference for the rear brakes vs only 4" on the much more heavily worked fronts.
285/35-20 is half an inch taller than 265/40-19, and that amount taller of a tire plus the bigger 20" wheel is probably drawing attention away from the fact that the 285/35 has about a quarter inch less sidewall than a 265/40.
The optical games designers play . . .
Norm
Last edited by Norm Peterson; 02-27-2014 at 08:37 AM.
#28
Lower profile sidewalls will not flex as much which should provide (depending on the tire) a controlled linear failure when the limits of the tire are reached, which is what many professional test drivers call the FUN factor in driving because the rear will swing out on you but, will allow for the driver to reign it back in and plus sizing will require the proper width to provide more contact with the tarmac on a wider surface area (AKA Drift). On a taller Profile When the limits are reached then at that point of failure with more flex on the sidewall can result in a catastrophic failure of the tire bead separating under repeated extreme loads. This of course applies to a road course type setup or a street setup where the driving can often be spirited and take a path that is far from a straight line. Driving on Twisties with acute Apex's and sweeping curves benefit from a wider cross section and lower sidewall coupled with the proper suspension. However road feel will be amplified...so beware of potholes.
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Last edited by Cruzinaround; 02-27-2014 at 12:55 PM.
#29
Lower profile sidewalls will not flex as much which should provide (depending on the tire) a controlled linear failure when the limits of the tire are reached, which is what many professional test drivers call the FUN factor in driving because the rear will swing out on you but, will allow for the driver to reign it back in
Any tendency for tailhappiness places a greater demand on driver skill to be able to rein it back in, because it all happens faster and with less warning. (and once you "catch" it, you have to be ready for an equally if not more sudden spin in the opposite direction).
On a taller Profile When the limits are reached then at that point of failure with more flex on the sidewall can result in a catastrophic failure of the tire bead separating under repeated extreme loads. This of course applies to a road course type setup
The main thing to realize is that taller profile tires give more warning (tires squealing, mushy steering response) as their limits are approached. Most people then do the sensible thing and not drive quite that hard any more unless they're avoiding some kind of accident.
It's probably harder to break a tire bead by "hard driving" than you think, even at near-zero psi. Never mind how I might know this.
Norm
#30
Failure? I suspect you're talking about tire behavior around peak grip, which can be a linear increase in grip up to just before it goes away (IOW, peaky) or a much more gradual transition that starts a lot earlier at lower g's and gives the average driver extra margin against losing it completely.
End Goal being a slow degradation of grip after its exceeded conditions for peak grip to where its predictable and easy to recover from.
Any tendency for tailhappiness places a greater demand on driver skill to be able to rein it back in, because it all happens faster and with less warning. (and once you "catch" it, you have to be ready for an equally if not more sudden spin in the opposite direction).
Unseating the bead might happen if the tire in question is badly enough underinflated but is unlikely otherwise.
Unseating the bead might happen if the tire in question is badly enough underinflated but is unlikely otherwise.
Unseating the bead would likely happen when the failure results in "hitting the wall" or "the Curb" or any irregularities on the tarmac surface that would cause the tire sidewalls to crumple and fold.
Then again the same can Happen with a lower profile sidewall or even a bent rim, but the linear failure again allows for a lesser skilled driver the benefit of more opportunity to recover.
The main thing to realize is that taller profile tires give more warning (tires squealing, mushy steering response) as their limits are approached. Most people then do the sensible thing and not drive quite that hard any more unless they're avoiding some kind of accident.
It's probably harder to break a tire bead by "hard driving" than you think, even at near-zero psi. Never mind how I might know this.
Norm
It's probably harder to break a tire bead by "hard driving" than you think, even at near-zero psi. Never mind how I might know this.
Norm
Tire design is driven by the faster performance vehicles... and clearly driving faster means that this is one area where the engineers are on point to go fatter and lower. Not for a 1/4 mile run but an extended long range at higher speeds. Which is why when the pinnacle of tire and wheel design is leaning more and more towards non pneumatic solutions with extremely low profiles and impact absorbing wheel designs to allow for those higher sustained speeds without a catastrophic failure.
If anything what engineers have learned is that outside of the short 1/4 mile expectations a taller profile tire actually hides much of the feedback response that is beneficial for staying on course.
They don't put tall tires on a Bugatti or a Hennessy or a SSC Aero or a Pagani... Or any Vehicle capable of sustaining these speeds WELL beyond a quarter mile simply because they can explode at sustained high speeds. Its an engineering thing.... I know.
Last edited by Cruzinaround; 02-27-2014 at 04:27 PM.