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Originally Posted by mahout
I and all other showroom stock racers will disagree with your braking suffering. In proven experience braking is improved because there is less deformation of the tire carcass at upper pressure limts. (don't misunderstand, I'm talking about 40 to 50 psug here, not 60 + psig)
The one change that we have noted in recent R compoundtires is their lighter weights and stiffer carcasses so pressures don't have to be raised as much on comp tires like they do on street tires. No one who doesn't like burning $10 bills to lite cigs runs race tires on the street.
And yes if you do drag race starts higher tire pressures simply don't hook up. But once you get going rigid carcasses beat flexible ones any day.
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So you're probably right on the money at 10% less than max sidewall pressure but you are likely biasing a little towards handling and mpg.
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I flat out disagree that all street tires are going to exhibit the same braking behaviours with the same pressure;
Despite your other statements tire pressures gernally have a lot to do with vehicle weight. Telling sombody to run First running 10% less than a max sidewall pressure is a pretty dangerous assumption. Depending on the tire they can vary from 35psi all the way up to 100psi (maybe more).
Secondly is going to affect harder summer rubber more dramatically than something like an all season tire.
Finally I think you are over looking the big picture, in order to increase MPG you need to reduce contact area or harden the tire to reduce rolling resistance. Both things will result in a comprimise in braking. The only thing I can even fathom why it would somehow defy physics is unless you are trying to say that the weight distributionof the vehicle when braking is somehow impacting that.
I will close on my final thoughts, my tires are a lower profile (40 series) tire. As a result I have a stiffer sidewall which most likely impacts my own findings. I will say that my handeling sweet spot is around 38-42psi, any more than that on my car and it starts sliding around hemeraging smoke and tread. I will acknowledge that maybe with a lager sidewall the pressure tolerances will go up, however it would still be nice to see some real world testing.