Stock Tires - Slips Easily

[strat61caster]

@torqdork

Tirerack has them listed for Prius. Maybe not specifically designed for Prius but were OEM spec.

They are also used on Fords, Lexus (GS), Mercedes (E-Class), BMWs (3 series, 5 series, X1), and Audis (A3, A6).

http://www.michelin.ca/tire-selector...p/tire-details

link2


Why did you link a comparison chart without the tire in question? The Primacy HP on the Toyobaru is a summer tire, the only Primacy's in that chart are a different compound all-season. Going to the correct chart puts the Primacy HP at #1 in it's class:

http://www.tirerack.com/tires/survey...ay.jsp?type=GT

You can slap Hoosier R6's on a Geo Metro, that doesn't diminish the fact that it's a highly regarded racing compound. The primacy's are severely underrated around here, they're durable, relatively comfortable, and good to learn on.

[Tenament05]

Originally Posted by paulca

They sound perfect for 'merikans.

us 'merikans are living great right now, dunno bout you guys over there...

[Jond63]

slip 'n' grip = <3

[torqdork]

@strat61caster, good catch, totally missed that.

What influenced me as much as anything was the test drive in the dealer demo with a willing salesman egging me on...at first. I took him to one of my favorite roads in the foothills a few miles away from the dealership and was surprised at how quickly the tires gave up grip on a dry, warm day. Based on my Prius experience with the same GreenX family of tire construction, I thought they'd be much worse in the wet so that's why I ordered the first set of replacements well before my car arrived.

I don't see what the OEM Michelins could teach an aspiring driver except how effective the system nannies are to save themselves from overwhelming lack of dry and wet grip that give the car it's signature "loose" character. Nothing much to learn and a bit upsetting to have the car balanced at corner entry only to have VSC/TRAC clamp down on the fun factor, understanding that they can be disabled eventually. I think tires are the first thing that most twin drivers I've met change out and are glad they did.

They're a good trading tool though. My local tire dealer gave me a generous trade allowance that made switching to a far better tire much better suited to the car very affordable.

[Demandred7]

I find that out of all the Michelin tires that I've owned, they all give up traction at the slightest hint of moisture on the ground. Maybe Pilot Super Sports are better, but, I remember switching to Bridgestone Potenza RE970's and their wet weather traction was far superior to any Michelin product that I've driven on.

[Sarlacc]

Originally Posted by Demandred7

Maybe Pilot Super Sports are better

They're better in the wet than the Primacy HP, for sure. But they're only great when properly warmed up and it's dry. IMHO, of course.

[strat61caster]

Originally Posted by torqdork

I don't see what the OEM Michelins could teach an aspiring driver except how effective the system nannies are to save themselves from overwhelming lack of dry and wet grip that give the car it's signature "loose" character. Nothing much to learn and a bit upsetting to have the car balanced at corner entry only to have VSC/TRAC clamp down on the fun factor, understanding that they can be disabled eventually. I think tires are the first thing that most twin drivers I've met change out and are glad they did.

essay inbound...

Tires with a lower grip threshold allow you to learn the dynamics of the vehicle at the handling limit at lower speeds than with grippier tires. When your grip thresh-hold is lowered you must drive more carefully, more precisely, more gently to maximize your tires: smooth is fast.

Higher grip tires can mask poor drivers inputs, I slapped some Dunlop ZII's on a few weeks ago, while someone sitting in a passenger seat would immediately notice I am faster than with the Primacy's I am realizing that my inputs are not optimal. Mistakes such as braking too early, turning in at the incorrect time or too aggressive/not aggressive enough are masked by the grip and result in some slight understeer due to the character of the car. But I know through my butt computer that I am not driving to the full potential of the grip and chassis I have.

With the Primacy's those mistakes would be obvious, punished, and correct technique rewarded as I carry maximum speed through the corner and steer the car out with the throttle instead of realizing that I am not unwinding the wheel soon enough and I can just plant my foot to the floor but it doesn't matter because the car just goes where I point it.

Not to mention managing non-optimal equipment is a good lesson for those looking at driving any vehicle that is not perfectly equipped at a high level (stock or classes with certain restrictions, endurance racing). Also sticky tires often don't break away progressively, once they hit the limit of adhesion they are gone and you're out of control, lower grip tires often lose traction progressively, you have time to correct mistakes and compensate, they communicate with you. A safer environment to explore the limits gives drivers confidence and confidence is the key to being truly fast.

Sure, someone who wants to show up to a couple track days per year and never time a lap will instantly love the upgraded rubber and it will be great for the duration of their ownership. I want to learn to be better and the Primacy's offer that opportunity.

I am not alone in this sentiment.

http://motoringconbrio.com/2011/12/1...-on-the-track/

http://flyinghorseracing.net/tag/tires/

Number 1 on this list is easier obtained with the Primacy's than stickier rubber:
http://jalopnik.com/ten-driving-tech...ster-837305612

This study was conducted testing the hypothesis, it contradicts my premise but it only covers step one of the process and the focus is on safety, not speed, over a very short time period (note it's a pdf):
S. de Groot, JCF de Winter: The effect of tire grip on learning to drive a racecar

From the "SCCA Solo II" book:
https://www.tirerack.com/features/so....htm#drivetips

Slow Down to Go Fast. A common problem when you're starting out is trying to take the tight sections too fast, and not staying in control. I still remember finishing a run and saying, "Well, I didn't go very fast, but it sure was smooth," only to find out I'd gone faster by a full second! Just be patient in the slow spots. They're slow spots, after all.


Brake hard in corners. Go ahead, squeeze the brakes hard. There's no morning coffee on your dashboard, or eggs in the front seat. Once you decide to slow down for the corner, don't waste any time. If you find yourself at a crawl and you're not at the corner yet, why, you've just found out that you can brake later. Locking up your tires will not make you stop faster, so squeeze the brakes and let them do the work, not your tires.

Adhesion. Don't ask too much of your tires. For any tire/pavement pair, there's only a certain amount of traction. We'll call that 100% traction. You can use up that traction with your throttle, your brakes or your steering wheel. So if you're going into a corner, using 100% of your traction to make the turn, what happens when you ask for more traction by applying the brakes? Either you won't brake or you won't turn. Or both. Same goes for accelerating out of a corner. Ease in the throttle as you ease out of the turn. So use full throttle and full braking only in a straight line. This goes back to slowing down to go faster, and brings us to...


Smooth Inputs. You may have noticed that I used the phrases "squeeze the brakes" and "ease in the throttle". This is where you have to change your mind-set about inputs to controlling your car. You need to convince yourself that you can make your car respond better by squeezing the brakes hard instead of standing on the brakes, by rolling in the throttle rapidly instead of stomping on the gas, by turning the wheel quickly instead of cranking it around. Subtle, but it will show up in how often your car is in control instead of scrubbing off speed pushing around a corner. And it will take a lot of practice to become second nature.

These things are easier to learn and accomplish on a less grippy tire and the lessons are easily applied when the upgrade happens.

Edit: I am of course assuming the driver is at a level where they are comfortable driving without the traction control on.

[Demandred7]

Originally Posted by Sarlacc

They're better in the wet than the Primacy HP, for sure. But they're only great when properly warmed up and it's dry. IMHO, of course.

Yeah, the Potenzas were supernaturally grippy in the wet (although, still breaking away progressively) and obviously even better in the dry.

[torqdork]

@strat61caster, I understand your focus.

My strategy is to mount the grippier, and therefore safer, wet/dry tire and then proceed first to an auto-x to learn chassis dynamics at lower speed limits. As Bobby Rahal says, safe is fast.

Then take those lessons and with a good instructor aboard, enjoy track days with much higher confidence and lower fear factor.

The trouble with learning driving lessons with the OEM tire is that they may well happen unexpectedly on public roads, catching even an experienced high performance driver unprepared. At that point it may become a difficult or impossible situation to control with or without aids compared to a higher performance tire that has a better chance of regaining control compared to the OEM tire that once sliding tends to take much longer to regain traction.

From my experience on an FR-S test drive and then on my FR-S over a mountain road I travel almost daily using three types of tires, OEM, high performance PSS and ultra-high performance RE-11A, IMO there's no question which tire is better suited for most drivers under all but snowy conditions, the PSS that can deal with anything from DD to SCCA auto-x to club track days.

[torqdork]

Originally Posted by Demandred7

I find that out of all the Michelin tires that I've owned, they all give up traction at the slightest hint of moisture on the ground. Maybe Pilot Super Sports are better, but, I remember switching to Bridgestone Potenza RE970's and their wet weather traction was far superior to any Michelin product that I've driven on.

Agreed. I had a set on an MR2 Spyder with an open diff and they performed much better in the wet than comperable Michelins, especially on corner exit.

[strat61caster]

Originally Posted by torqdork

The trouble with learning driving lessons with the OEM tire is that they may well happen unexpectedly on public roads, catching even an experienced high performance driver unprepared. At that point it may become a difficult or impossible situation to control with or without aids compared to a higher performance tire that has a better chance of regaining control compared to the OEM tire that once sliding tends to take much longer to regain traction.

I am surprised you feel that unsafe on the Primacy's, they have only surprised me twice and both were under extremely wet conditions and it was entirely my fault for not anticipating the road conditions. They performed excellently at AutoX and on the Track when expectations were properly set (i.e. I'm not going to beat Randy Pobst's time around Laguna Seca my first day out there).

You're not the first person who has said they feel unsafe on public roads with them, I'm really curious as to how someone with this opinion drives as I did not feel unsafe hurtling through turn 1 into turn 2 at Laguna Seca at 100+ mph with only the OEM brakes to slow me down.

To each their own.

[torqdork]

Originally Posted by strat61caster

...I'm really curious as to how someone with this opinion drives...

Smoothly enough to become SCCA street tire champion.

Maybe you weren't going fast enough at Laguna Seca?

[strat61caster]

Originally Posted by torqdork

Smoothly enough to become SCCA street tire champion.

Maybe you weren't going fast enough at Laguna Seca?

I most certainly wasn't

First day after all, was probably just barely under 2 minutes at the end of the day.



Just more proof that different strokes for different folks.

[torqdork]

I've never run Laguna Seca but plan to this June. One of the classic tracks for sure.