POLL: What will my 60-0 stopping distance be with Pilot Sport 4S 265/40R18s be?

[Daniel in SD]

Not shown on this screen but 60-0 was 106.85 feet for this stop.

 

[AlanSubie4Life]

It’ll be interesting to compare the brake feel when/if I ever get my car. Maybe the larger pads make it easier to modulate. But as Daniel says different pad compounds can definitely give the brakes more initial bite, and a different feel. They also may tend to eat the rotors faster.

 

[AlanSubie4Life]

Not shown on this screen but 60-0 was 106.85 feet for this stop. View attachment 347906

You’re going to wear out your brakes and your tires! I guess it will balance the tire wear by scrubbing off the fronts.

 

[Daniel in SD]

You’re going to wear out your brakes and your tires! I guess it will balance the tire wear by scrubbing off the fronts.

Ha. That stop was also with low regen on. If you add the 0.2g of regen it would have stopped about 20 feet shorter, way better than your P3D+!

 

[ElectricGhost]

I surprised the 265 dont show much vs the 235s. The more you can log laterial G, 0-60, and 0-60ft so we can get and idea for how much 265s help vs 235s. Im considering putting 255 in the stock wheels vs getting 19x9.5s for 265s. Really appreciate the results your getting right now.

Also, my performance model 3 runs a 11.7X-11.8X on all season tires. Surprised that car and drivers test with the performance model 3 with pilot sport 4s tires was around 12

 

[Feathermerchan]

What are the two tire sizes we are comparing?
235/40-18 MXM4 on 18X8.5" wheels Tread width 8.5" (Tire Rack)
265/40-18 MP4S on 18X9.5" wheels Tread width 9.4" (Tire Rack)

Note that tread width does not have to follow section width.
(265/235) X 8.5 = 9.59 not 9.4

I have seen Michelin tires with different section widths and the same tread width.

Question for the group: I have seen where Tire Rack gives prohibitions and warnings about running summer tires below 40 degF. But I cannot find anything on Michelin's website for the MP4S tires. Is there no restriction?

If I can run MP4s in the winter, I'll buy some light 18" wheels and 235 size MP4S and call it a day.

 

[Knightshade]

Much below 40 summer tires turn into hockey pucks

If it's dry out and you drive very carefully, you'll still be ok down to at least the 20s but I wouldn't recommend doing it if you can avoid it.

if it's at all wet you're gonna have basically 0 traction

The Michelin A/S 3+ tests out nearly as good as the PS4 4S and while still not nearly as good as a dedicated snow tire in snow is at least an all-season that's fine in light winter weather while also being pretty decent in summer (and longer tread life too)

 

[Daniel in SD]

What are the two tire sizes we are comparing?
235/40-18 MXM4 on 18X8.5" wheels Tread width 8.5" (Tire Rack)
265/40-18 MP4S on 18X9.5" wheels Tread width 9.4" (Tire Rack)

Yes but 235/45 for the MXM4s of course. I suspect that the additional width doesn't help much with braking distance. Maybe I'll be able to test back to back with the 235 width PS4S at some point.
I don't have to worry much about it getting below 40 degrees here. The air temperature might get down to 40 a few nights of the year but I doubt the pavement ever gets that cold. I'm keeping to the aeros and MXM4s for trip where I need more range or there's cold weather.

 

[Feathermerchan]

Edited original above to show 235/45-18 MXM4

What are the two tire sizes we are comparing?
235/45-18 MXM4 on 18X8.5" wheels Tread width 7.8" (Tire Rack)
265/40-18 MP4S on 18X9.5" wheels Tread width 9.4" (Tire Rack)

Note that tread width does not have to follow section width.
(265/235) X 7.8 = 8.8 not 9.4

Is that what you meant?

 

[usofrob]

I wonder how much tire pressure would effect the performance. I wonder with wider tires, if you need to run lower psi to get more grip.

 

[remlemasi]

@Daniel in SD , I have a couple questions as I am thinking of moving to PS4S once the MXM4 are done.

1) The tires look nice and flush with the fenders in your photos. I assume you don't have any spacers installed and it's all due to the tire sidewall difference?

2) Tire specs shown a rim width range of 9-10.5" for 256/40ZR18, but you have them on 8.5" wheels. You don't see or expect any issues with this combo? We know the compound can handle a lot of grip and I'm concerned about sidewall rolling over under hard cornering.

Now knowing what you know about braking distances and having driven on them for a week or so, would you go with 235/45ZR18 the next time around? Do you think it would contribute to a stiffer sidewall and potentially more precise turn-in and steering feel?

EDIT: Sorry I just went back or re-read the posts and realize you don't have stock 18" Aeros anymore! Color and spoke design is close enough that I totally missed that fact. Please disregard...

 

[Jedi2155]

I wonder how much tire pressure would effect the performance. I wonder with wider tires, if you need to run lower psi to get more grip.

There should be a sweet spot for maximum grip because too much pressure you lose surface area as the tire pillows out. Too little it'll start cupping or something of the sort. The best grip would be where you can maximize tire road contact area.

 

[dfwatt]

There should be a sweet spot for maximum grip because too much pressure you lose surface area as the tire pillows out. Too little it'll start cupping or something of the sort. The best grip would be where you can maximize tire road contact area.

Not quite, as road contact patch steadily increases as TP declines. One of the great paradoxes (or seeming paradoxes anyway) is 'why doesn't lower tire pressure make for better cornering and braking' given that your contact patch area (which obviously impacts max lateral and vertical loads before breaking the traction envelope) is mostly inversely proportional to your tire pressure?? Higher pressures mean lower contact patch area? How can that make the tire perform better?? Seems a bit weird when you think about it in those terms, but it turns out that the contact patch stability (resistance to squirm/bunching up/rolling over) under extreme load is roughly proportional to TP, so max performance sits at an intersection between declining contact patch area vs. increasing contact patch stability. For a lot of tires that's somewhere in the high 30s to low 40s lbs territory, but most tires probably in the 40s if the tire is not under-loaded. On my IS350, I actually dropped TP on the rears a bit, as the tire (255/40-18) was so lightly loaded relative to the fronts that the rear would tend to break free in corners at higher pressures.

What's a bit weird is the lack of hard empirical research about this sweet spot across brands of performance and track tire. You'd think we'd know this value for tires, but it seems this info is hard to find, and mostly it's all anecdotal. And of course the other problem is that those best performance pressures almost always result in an undesirably exaggerated crown wear pattern.

Another interesting issue here is low rolling resistance, which of course is many tread and sidewall variables but where higher pressures are a cheap way to get there without making a lot of other changes that might impact traction negatively. The Michelin Pilot Sport 4S, arguably the best street performance tire out there, is set to run a 42 lbs by Telsa. I suspect that Michelin made some changes to the Super Sport to mitigate and even out crown wear at higher pressures, so that the 4S could be run at those pressures chronically and still wear fairly evenly. Don't know that for fact, but it's my best guess, as no previous Super Sport was recommended to be run chronically at those pressures.

 

[Jedi2155]

What's a bit weird is the lack of hard empirical research about this sweet spot across brands of performance and track tire. You'd think we'd know this value for tires, but it seems this info is hard to find, and mostly it's all anecdotal. And of course the other problem is that those best performance pressures almost always result in an undesirably exaggerated crown wear pattern.

Another interesting issue here is low rolling resistance, which of course is many tread and sidewall variables but where higher pressures are a cheap way to get there without making a lot of other changes that might impact traction negatively. The Michelin Pilot Sport 4S, arguably the best street performance tire out there, is set to run a 42 lbs by Telsa. I suspect that Michelin made some changes to the Super Sport to mitigate and even out crown wear at higher pressures, so that the 4S could be run at those pressures chronically and still wear fairly evenly. Don't know that for fact, but it's my best guess, as no previous Super Sport was recommended to be run chronically at those pressures.

So my only question is here in regard to the Pilot 4S, is that its been mentioned that the edges of the tire are optimized for cornering grip with a different compound, while the center of the tire utilize a harder compound for LRR that Tesla has specced in our tires that way you get the best of both worlds (this is also the same in all Pilot 4S, but Tesla's center patch may be harder than normal PS4S tires). Proper inflation pressure still seems to be my thoughts and following Tesla's 42 PSI number would make logical sense.

 

[AlanSubie4Life]

max performance sits at an intersection between declining contact patch area vs. increasing contact patch stability.

Presumably it's something along these lines that results in wider tires being necessary for more straight-line acceleration? Traction is not currently an issue for the P3D, but I was wondering about this the other day. The contact patch is wider and shorter for a wider tire for a given PSI with the same vehicle weight, but not any larger area. Somehow that must be more "stable" for high acceleration g forces? I guess it's the same as contact patch stability, but perhaps the pavement stability also fares better if the heat & acceleration is spread across a wide patch? I've seen melted pavement in the past...though probably that was from burnouts; wouldn't be enough heat generated for a proper acceleration run.

Again, one of these days I'll get around to testing the 60-0 with my stock 235s and see how they compare to @Daniel in SD . Hopefully we can do side-by-side comparisons to eliminate a bunch of variables. For now, I've been saddled with a variety of boring 0-60 experiments.

 

[Jedi2155]

What I'd love to see a Stealth P3D versus a P3D+. How much of a difference is those MXM4s vs. PS4S tires.

 

[AlanSubie4Life]

What I'd love to see a Stealth P3D versus a P3D+. How much of a difference is those MXM4s vs. PS4S tires.

Essentially we'll have that after my experiment (since the AWD isn't any different than a Stealth P3D presumably), though it is true that it wouldn't be in side-by-side controlled conditions (the location will be the same though). I'd have to ask @Daniel in SD to put his MXM4s back on!

 

[ℬête Noire]

Not quite, as road contact patch steadily increases as TP declines. One of the great paradoxes (or seeming paradoxes anyway) is 'why doesn't lower tire pressure make for better cornering and braking' given that your contact patch area (which obviously impacts max lateral and vertical loads before breaking the traction envelope) is mostly inversely proportional to your tire pressure?? Higher pressures mean lower contact patch area? How can that make the tire perform better?? Seems a bit weird when you think about it in those terms, but it turns out that the contact patch stability (resistance to squirm/bunching up/rolling over) under extreme load is roughly proportional to TP, so max performance sits at an intersection between declining contact patch area vs. increasing contact patch stability. For a lot of tires that's somewhere in the high 30s to low 40s lbs territory, but most tires probably in the 40s if the tire is not under-loaded. On my IS350, I actually dropped TP on the rears a bit, as the tire (255/40-18) was so lightly loaded relative to the fronts that the rear would tend to break free in corners at higher pressures.

What's a bit weird is the lack of hard empirical research about this sweet spot across brands of performance and track tire. You'd think we'd know this value for tires, but it seems this info is hard to find, and mostly it's all anecdotal. And of course the other problem is that those best performance pressures almost always result in an undesirably exaggerated crown wear pattern.

Another interesting issue here is low rolling resistance, which of course is many tread and sidewall variables but where higher pressures are a cheap way to get there without making a lot of other changes that might impact traction negatively. The Michelin Pilot Sport 4S, arguably the best street performance tire out there, is set to run a 42 lbs by Telsa. I suspect that Michelin made some changes to the Super Sport to mitigate and even out crown wear at higher pressures, so that the 4S could be run at those pressures chronically and still wear fairly evenly. Don't know that for fact, but it's my best guess, as no previous Super Sport was recommended to be run chronically at those pressures.

So what are the implications of this for chalking tires? Do you actually want to see a bit more chalk left on the outside, or does that all go out because hard cornering should move that back towards wanting to see even chalk removal across the tire because you're pushing it hard enough to deform anyway so you want it to deform to "normal"?

 

[Knightshade]

What I'd love to see a Stealth P3D versus a P3D+. How much of a difference is those MXM4s vs. PS4S tires.

In a drag race? Basically 0. Both folks have done 0-60 runs and seen similar times. The car isn't traction limited when launching even on the all seasons. In stopping distance per the thread? Quite a bit, couple dozen feet.

 

[dfwatt]

What I'd love to see a Stealth P3D versus a P3D+. How much of a difference is those MXM4s vs. PS4S tires.

The difference is HUGE. The only way to appreciate is drive the car with the MXM4s, then swap out to the PS4S. I wouldn't even think about driving my P3D+ with any other street tire. I'd encourage you to do this test if you have any questions.