[Aronis]

Originally Posted by shawnhayes

It depends on what you call "crisper" I guess. At less than 0.5g, I would say you are right. Turn in will be a little quicker.

As the speed, and the g's increase, ANYWHERE near 40 psi gets squirrely on most street tires (even on hot pressures). The excess air keeps the tire from "working as designed". Most manufacturers have an "optimal" road pressure. This is usually achieved after about 20 minutes of driving on a car in 70 degree weather with the tire at the recommended cold pressure of the car (almost always 32 psi, unless you're talking about a weirdo like the i3 - I had two of them). Almost every other condition becomes a compromise.

https://www.firestonecompleteautocar...ate-car-tires/

On the track, trackrats like I am, almost always note that anything DOT legal starts to slide at anything over 40 psi. Hot or cold. Despite physics (which doesn't give a shit about size of contact patch), real cars have "rollover" on tires. As the car corners, the tires roll over onto the outside edges of the tire (on the outside of the turn radius). The inner tires roll over on the inside edge. Traction seems to be compromised. Physics says that as long as the friction coefficient doesn't change, it shouldn't matter. But it DOES. Otherwise, we'd all have bicycle tires on our cars.

I'm sure the reasons are more complicated, but both car and tire manufacturers agree. Inflate to recommended pressures and stay there.

Shawn

Excellent. I love to learn.

Mike

[shawnhayes]

Originally Posted by Aronis

Excellent. I love to learn.

Mike

The basics:

https://motoiq.com/the-physics-of-tires/

Advanced past that..

https://www.tirereview.com/the-physi...nering%20force.

More with Mike Kojima..

https://motoiq.com/mike-kojima-guest...on-suspension/

Shawn

[omgmike]

Originally Posted by bruza

Timely post, I just had my PS4s installed Thursday. I was surprised when they set my new tires at 34 PSI cold.

I usually run a couple lbs less but after seeing this thread I’ll stay at 34.

Goes w/o saying, PS4s >>> P ZERO’s

Jealous! Still waiting on my P Zeros to need replacement so I can get back to Michelins.

[NoMods]

Winter wheels at 35 and Summers at 33

[SenorFunkyPants]

I must admit that for street driving I like to add a little over the recommended pressure for the extra sidewall support that it gives and the resulting slightly crisper feel.
But sure you can feel the grip start to go off when the road surface temps are high and you are pushing on.
Interestingly, Goodyears early low profile wide tyres suffered from high wear in the centre of the tread due to the tendency for that part of the tyre to balloon out at high speed which had to be countered by raising the tyre pressures.

[Aronis]

A request from the group.....

I have been noticing that the "recommended" tire pressure on the car's dash CHANGES based on ? Not sure.

Last weekend I checked and it said 36 in front, 37 in rear. Yesterday it said 37 in front and 38 in rear. It was 50 degrees outside.

I guess the car is looking at ambient temp and tire temp and then giving a recommendation?

Can you guys look and see what your car says and note the ambient temp.

Mike

[micvite]

Originally Posted by shawnhayes

Good call. But, if you ARE going to run on the autobahn in the summer for more than a few miles, those high pressures give more air to absorb the heat. That's why that setting is there (I guess there is Montana as well).

Shawn

Montana got rid of the no limit quite a few years back due to some ass that fought 2 speeding tickets with the excuse "there's no speed limit"

[shawnhayes]

Originally Posted by Aronis

A request from the group.....

I have been noticing that the "recommended" tire pressure on the car's dash CHANGES based on ? Not sure.

Last weekend I checked and it said 36 in front, 37 in rear. Yesterday it said 37 in front and 38 in rear. It was 50 degrees outside.

I guess the car is looking at ambient temp and tire temp and then giving a recommendation?

Can you guys look and see what your car says and note the ambient temp.

Mike

There go. That do?

Shawn

P.S. - it also depends on the <100mph and > 100mph setting in the idrive.

[micvite]

Originally Posted by shawnhayes

There go. That do?

Shawn

P.S. - it also depends on the <100mph and > 100mph setting in the idrive.

And whether you have the m drivers package too.

[Maverik259]

Originally Posted by shawnhayes

There go. That do?

Shawn

P.S. - it also depends on the <100mph and > 100mph setting in the idrive.

LMAO, YES!...is this a track day with a lot more right hand turns? where are you driving that you're getting 190 tire temps! Even during the summer i barely get above 125 on normal driving.

[shawnhayes]

Originally Posted by Maverik259

LMAO, YES!...is this a track day with a lot more right hand turns? where are you driving that you're getting 190 tire temps! Even during the summer i barely get above 125 on normal driving.

This is VIR on my 2018. Unfortunately, that left front not ONLY gets heat from a clockwise track, it is heated by the oil cooler in the left front bumper (very unfortunate placement).

If you need documentation from the CS, I can supply that again soon. Going back to VIR in November.

Shawn