Tire Contact Patch and Vehicle Stability - Alignment

[ZDan]

Originally Posted by treedodger

IMHO, I would suggest that the quickest way to make a novice safe on track is for them to spend enough time on the skidpad so they can catch a slide without having to think about it...and it's a lot of fun!

Absolutely! Wet and dry skidpad training for novices *before* getting on the track is a GREAT idea, but I've only been at one track day where that was done (BMW CCA event at Mont Tremblant a long time ago...).

[churchx]

Wouldn't for skidpad experience also driving on snow/ice for those living where real winters are, if some sliding needs to be experienced? Or first "showing the ropes" with instructor at the wheel and doing some intentional skids & corrections so to feel skid symptoms and needed timing/extent of correction?

[racingfool]

Originally Posted by ZDan

How old do you reckon that is?

My guess would be 44 years.

Originally Posted by ZDan

Most modern "Extreme Performance" tires have *amazing* grip at very high slip angles.

You're suggesting that higher grip tires are more forgiving at the limit?
I think the limit is just higher and novices are less likely to reach it.

Remember the Hoosier bias ply "autocrossers"? Now those liked high slip angles.

[ZDan]

Originally Posted by racingfool

My guess would be 44 years.
You're suggesting that higher grip tires are more forgiving at the limit?
I think the limit is just higher and novices are less likely to reach it.

Yes, I am saying that good extreme perf tires like RE71R, A052, etc. *are* quite forgiving at the limit, much more so than most passenger car tires.
I think that when novices *do* reach the limit on such tires, they are more likely to regain control vs. lesser-performing street tires.

Remember the Hoosier bias ply "autocrossers"? Now those liked high slip angles.

Ha ha, my first couple/few track days with the 240Z back in the mid-90s were on Hoosier bias-plies! Interesting driving 90 miles to/from the track on those tires...
Either highest-performance street radials or radial Hoosiers since then.
For sure the max grip and also the post-sliding grip of the best track-oriented street tires improved pretty dramatically from the Z1 *spec on.
Last event I ran Hoosier A7s, first time I'd run Hoosiers since R3S03 days... I found the A7s to also be quite forgiving at the limit and not at all peaky in terms of non-sliding transitioning to sliding grip.

[racingfool]

Originally Posted by ZDan

Yes, I am saying that good extreme perf tires like RE71R, A052, etc. *are* quite forgiving at the limit, much more so than most passenger car tires.

This, from treedodger's link, is from 2019.

If you find yourself spinning, you’re getting surprised by loss of traction. To combat that surprise you need tires with more compliance.

Racing tires have the most grip, but they also have the most change in grip. Once the optimal slip angle is exceeded,
grip falls away very quickly. On the opposite end of the spectrum is the street tire. It has low grip, but a very gradual loss of traction.

[ZDan]

Originally Posted by racingfool

This, from treedodger's link, is from 2019.

I disagree w/ treedodger's link! If we are talking about on-track at-the-limit driving on street tires, I think that even Max Perf tires are generally too soft-sidewalled. Particularly in transitions, more sidewall compliance makes the car more unsettled. More compliance => more lateral motion of the car and more lateral velocity that has to be arrested before developing full lateral grip. You're more likely to spike over the tire's lateral grip capacity. This is my impression anyway...
FWIW I went back-to-back-to-back with Conti ExtremeContact Sport and Hoosier A7s on day one, then back-to-back ECS/A7 on day 2 at Palmer a few weeks back. The Contis are too squishy... The Hoosiers were more fun and the back of the car felt more planted through transitions even at much higher speeds.

This is my opinion, but I think even novice newb students are better off with tires designed more for track usage than on more street-oriented tires. Not Hoosiers mind you, but tires like the Hankook RS4, vs. softer-sidewall tires with smaller tread blocks.

[treedodger]

Originally Posted by churchx

Wouldn't for skidpad experience also driving on snow/ice for those living where real winters are, if some sliding needs to be experienced? Or first "showing the ropes" with instructor at the wheel and doing some intentional skids & corrections so to feel skid symptoms and needed timing/extent of correction?

While I think both of these help (snow/ice and rides), IMO the biggest benefit comes from time on the skidpad with your track car learning its dynamics. Once the driver can catch slides without thinking about it, they are substantially safer on the track. It took me about 2-3 skid pads days to get to this point, but maybe I'm a slow learner.

My experience is new drivers will learn car control 10x faster on the skidpad than on the track, without risking a crash. I have seen way too many cars hit the the k-rails because drivers had more speed, than car control skills.

[gcmak]

Originally Posted by treedodger

While I think both of these help (snow/ice and rides), IMO the biggest benefit comes from time on the skidpad with your track car learning its dynamics. Once the driver can catch slides without thinking about it, they are substantially safer on the track. It took me about 2-3 skid pads days to get to this point, but maybe I'm a slow learner.

My experience is new drivers will learn car control 10x faster on the skidpad than on the track, without risking a crash. I have seen way too many cars hit the the k-rails because drivers had more speed, than car control skills.

"Once the driver can catch slides without thinking about it, they are substantially safer on the track." That's really the thing I have to work on. My reactions are too slow, my brain says to correct after too much slip angle has occurred, because my brain's first reaction was to not react. It has to become more second nature.

Originally Posted by ZDan

I disagree w/ treedodger's link! If we are talking about on-track at-the-limit driving on street tires, I think that even Max Perf tires are generally too soft-sidewalled. Particularly in transitions, more sidewall compliance makes the car more unsettled. More compliance => more lateral motion of the car and more lateral velocity that has to be arrested before developing full lateral grip. You're more likely to spike over the tire's lateral grip capacity. This is my impression anyway...
FWIW I went back-to-back-to-back with Conti ExtremeContact Sport and Hoosier A7s on day one, then back-to-back ECS/A7 on day 2 at Palmer a few weeks back. The Contis are too squishy... The Hoosiers were more fun and the back of the car felt more planted through transitions even at much higher speeds.

This is my opinion, but I think even novice newb students are better off with tires designed more for track usage than on more street-oriented tires. Not Hoosiers mind you, but tires like the Hankook RS4, vs. softer-sidewall tires with smaller tread blocks.

I've not had the seat or tire times as you have but in my limited experience both as a driver and more so as a passenger, I tend to agree with you that tires with softer sidewalls not only unsettle the car more on a tighter track with more left/right transitions but also in long sweepers where any adjustments mid-corner feels a bit like jello. I noticed this effect in a few M cars running PS4S tires compared to something like an R-S4 or 71R or R888. I was able to ride back to back in 2 M2's one with PS4S and one with stock PSS and I much prefer the stock PSS - the sidewalls seem to hold up nicer.

The stock tires I had didn't feel as jello like as I would have believed, but its also because they have a lower grip limit, so that might help to reduce the effects of a softer sidewall. I'll certainly get different tires next time, currently considering RT660 or R-S4, but in stock sizes.

[churchx]

treedodger: i did my share of learning on relatively safe (=long grass runoff zones) technical track (due it originally made for karts, not too big, but many tight turns with short straights). For me, similar to you, similar first 2-3 trackdays i did spun 2-3 times each, but by then i drilled down bits like how much i overpushed to spun, what symptoms signaled that and in what fashion/tempo/extent to correct to stop spin/restore grip. But opposite to you, that learning on track imho tought me those bits faster and in more tailored/linked to track driving way then one lesson of safe driving and emergency maneuvers that included tries to understeer/oversteer on wet skidpad. There i just did that drill twice as rest in group participating those courses .. but it didn't left me any reflexes for long term. Maybe too little, insufficient tries, just single wet config .. but i learnt more on track later on. Hence my idea that faster way to correct grip loss would be first by instructor showing intentionally with learner as passenger to show symptoms & inputs/tempo of correction, and then let one try on safe enough actual track or safe enough specific turns of track few times. Skidpad .. if it was like i had, see no sense in such. Maybe if it was repeating many many times during day, maybe if with varied grip level (dry/wet) and varied speed/radius .. but only important bits that i kept from those courses was to be able to brake hard & importance of right seating pose/right adjustment of wheel/seat/right hold of steering wheel, and that's mostly it.

[treedodger]

I don't think I have anything to argue over here.

If your track has corners with lots of safe runoff room, you can accelerate your learning by running crappy tires and adding enough toe out to the rear to practice oversteer on every corner! HaHa (sort of joking...) This video is my inspiration:

Originally Posted by churchx

treedodger: i did my share of learning on relatively safe (=long grass runoff zones) technical track (due it originally made for karts, not too big, but many tight turns with short straights). For me, similar to you, similar first 2-3 trackdays i did spun 2-3 times each, but by then i drilled down bits like how much i overpushed to spun, what symptoms signaled that and in what fashion/tempo/extent to correct to stop spin/restore grip. But opposite to you, that learning on track imho tought me those bits faster and in more tailored/linked to track driving way then one lesson of safe driving and emergency maneuvers that included tries to understeer/oversteer on wet skidpad. There i just did that drill twice as rest in group participating those courses .. but it didn't left me any reflexes for long term. Maybe too little, insufficient tries, just single wet config .. but i learnt more on track later on. Hence my idea that faster way to correct grip loss would be first by instructor showing intentionally with learner as passenger to show symptoms & inputs/tempo of correction, and then let one try on safe enough actual track or safe enough specific turns of track few times. Skidpad .. if it was like i had, see no sense in such. Maybe if it was repeating many many times during day, maybe if with varied grip level (dry/wet) and varied speed/radius .. but only important bits that i kept from those courses was to be able to brake hard & importance of right seating pose/right adjustment of wheel/seat/right hold of steering wheel, and that's mostly it.

[TommyW]

Originally Posted by treedodger

My experience is new drivers will learn car control 10x faster on the skidpad than on the track, without risking a crash. I have seen way too many cars hit the the k-rails because drivers had more speed, than car control skills.

While this is true, the difference is skidpad oversteer is expected and induced where oversteer on the track is usually a surprise so there is the element of surprise that separates the skidpad from the track. Skidpad definitely helps however there are other elements involved which generally comes with confidence and experience. The best aid in either scenario is hard tires.

[ZDan]

Originally Posted by TommyW

While this is true, the difference is skidpad oversteer is expected and induced where oversteer on the track is usually a surprise so there is the element of surprise that separates the skidpad from the track. Skidpad definitely helps however there are other elements involved which generally comes with confidence and experience. The best aid in either scenario is hard tires.

Skidpad practice will train muscle memory on how to deal with loss of grip at either end with both the steering wheel and the throttle. Highly highly highly recommended...

What do you mean by "hard tires"? Stiff sidewalls, or hard compounds that wear like iron and grip like, um, iron?

Still giving a hard vote for modern "Extreme Perf" rubber for track use. Resistance to overheating and residual sliding grip ftmfw...

[TommyW]

Originally Posted by ZDan

Skidpad practice will train muscle memory on how to deal with loss of grip at either end with both the steering wheel and the throttle. Highly highly highly recommended...

What do you mean by "hard tires"? Stiff sidewalls, or hard compounds that wear like iron and grip like, um, iron?

Still giving a hard vote for modern "Extreme Perf" rubber for track use. Resistance to overheating and residual sliding grip ftmfw...

as mentioned skid pad is a valuable Learning tool. Tire wise something without a lot of grip is preferable for learning slip angle management at a comfortable speed.

[ZDan]

Originally Posted by TommyW

as mentioned skid pad is a valuable Learning tool. Tire wise something without a lot of grip is preferable for learning slip angle management at a comfortable speed.

For me, "as an instructor" (nyuk), I strongly prefer my students to be on track-appropriate tires.