Overthinking

Started by Petrus, September 25, 2022, 08:45

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Petrus

The fabled, almost mythical evvah so important balance of our little cabrio. Yes, the tiniest of change in weight (distribution) et al is noticeable.
Tyres too OFCOURSE!

Although I applaud Toyota for the neat little package they sold to the customers, me personally prefer less understeer, tbh lóath understeer so rebalancing it is.
Have it quite nicely sorted to my taste now.
....and of course the tyres wear, Not so much the tarmac wearing the tread as the heat cycling degrading the properties: The trusty AD08Rs get noticeably harder. It is not a problem as they remain predictable and it is the same front/rear so the holy balance is unchanged. Still...
Also not all thát pleased with the fronts rubbing when I push. Yes, yes, it is getting just a bit less as grip allows less pushing. Still...
So, thinking about fresh wubbah.

But, but .... no more AD08R and the replacement is supposed to have less grip  :-\
Going A052 for the road, hmmm.
Will ask for a quote on both.

That brings me to the size. Size doés count  :))
Currently running 195 up front in the quest for less understeer. Also went 55 section instead of 50 for same reason. It does run bthough. Quite annoying. So what about 50? Is lower so should rub less no?!
Ah, but a smaller diameter also means less footprint meaning less grip meaning more oversteer. A whole 1.5%  :o
Has a lower sidewall though, 5% lowers so 5% stiffer giving as much more feel.
Oh my...

In the real world of many on this forum it is mostly, pardon the word, bs. Several even combine two different types of tyres on front vs rear axle.
I thínk I am overthinking things  O:-)
Best keep laying the rubber down and enjoy the balance  :))  :))

Joesson

Overthinking? Well that may be the case, but there has long been alternatives for whatever and while some may jump straight in for the first available, best looking, heaviest, lightest, longest, straightest etc. nowadays we have the www to aid us with our choice!
Tyres, the item mentioned, for example are fortunately, or otherwise, the subject of continuous development. Whether that is progressive or not is open to debate.
The tyres referred to have gained approval from members on this Forum and those Members would likely buy again, but development means that is not an option.
Different tyres, front and rear, was iirc mentioned by @Carolyn a while ago, and why not, each end serves a different function and Mr T decided different widths and later different diameters were required front and rear. But, any mix I suggest should be very carefully considered.
I am aware that the selection of wheels and tyres is a consideration in the design and development of vehicles and much time and cost is likely expended in getting it right, for all customers and situations. Therein lies the problem.
Thinking then, I suggest, is a continuous process and as situations change the process necessarily requires repeating.


Petrus

#2
Good point that ´development´.  It has several aspects imo. Technical, commercial, environmental but also progressing insight per example.

The tyres are just about the best point in case.
Take the AD08R vs AD08RS; ´development´ yes but the advance is not in grip.

The development of grip of tyres is AWESOME btw.
In the formulae of traction, friction we were tought at school it is quite a simple thing with the friction being the load x the friction coëfficient.
The theory then is that centrifugal force and gravity equalling out are the cornering speed limit.
When I started racing nid seventies it was not like that! Sirfaces were neither flat nor smooth, nor forces constan, nor suspension perfect nor anything inalastic.
To complicate it all, rubber has a tricky property called ´load sensitivity´.

In those days the Dunlop TT100 was cutting egde, soon edged out by Michelin racing rubbers becoming available for even road use! Enter temp. sensitivity and heat cycling  ::)  :o

Anyway and noway that a 45 degree lean angle with centrifugal force and gravity equalling out was a realistic limit on the road or racing as that was more often than not on temporarily closed off roads!

Even today, with high hysteresis rubbers and 60 degree lean angles for MotoGP bikes, on the real world road it is pretty much a traction limit that cornering at 1G.

It is when bráking that we most markedly notice the HUGE development in traction of rubbers. Because of the weight transfer the high hystereris comes into its own and we cán see decelerations exceeding 1G.

Despite my tongue in cheek harping on about balance, it is the braking which is my priority. I happily, well unhappily, pay extra for a shorter stopping distance. This is the only reason why I am a bit pee´ed off by the new AD08RS and would consider using A052s.

 

 




Ardent

Tyres really are a bottomless rabbit hole.

As a bare minimum, there are as many variables as people looking to buy. Each will have their own priorities.

I had a set of the Yoko AD08R. Stunning. Comical levels of grip when new. Bloody awful at the end of their working life.
As per Petrus, heat cycles etc etc, and additionally not so favorable UK weather.

I am now on Rainsports. Do they offer as much grip as the Yoko? hell no. Do they still offer more than enough grip for my ability and context in which they are used, hell yes.

I have Yoko Fleva on my daily and when the rainsports wear out, I will look to replace with the Fleva's if I can get the sizes.

If the original AD08R was available, would I buy again? Yes. Will I buy the new "improved" version? No.

Dev

There are cheap tire brands in my country that have ultimate grip but they are horrible driving tires.
Grip is only one of many attributes on judging tires. What I look for in a tire is feel with plenty of warning. I also don't want my tires to get noisy as they get old. My current set feels like the original OEM but with more grip and stiffer sidewalls. No issues with heat cycle or any of the quirks you get with extreme category of tires.
 With tires that have soft sidewalls and ultimate grip I felt like I had to drive much faster to get my thrill but now I can drive slower and safer to get the same resistance which feels just as nice. If I had to push it I could do that also with plenty of grip headroom but since seconds between tires in the same category is meaningless unless you race, the tire with more grip is meaningless. Quality of the tires character is far more important.

Nvy

What about toyo 888 square 205?

Petrus

I get what you mean Dev and it is why I left the NoGrip Gladial ElCheapo brand tyres on when I first got the car. To get to grips  ;D  with the car at lower speeds.

Same thing Toyota did with the GT86 on eco rubber from the shop floor.


Yet:

Quote from: Dev on September 26, 2022, 00:59but since seconds between tires in the same category is meaningless unless you race, the tire with more grip is meaningless. 

The cyclist you could have stopped for may differ in opinion.
As I wrote, stopping distance is higher on my priority list than cornering speed.
Next comes more margin with éverything. Even a minor mishap easily adds up to more than the premium for premium grip.
Basically am at the same penny wise pound fool with the tread left and grip going down. They are still relatively grippy though; more so than all seasons and the replacement have been ´developed´.

Apparently Yokohama has seen the need to change tactics too as they introduced the Neova AD09 this summer. Announced them in sizes from 15 to 19". Sofar 17 is the smallest diameter and nothing overseas yet.

@all  have a look on the interweb for stopping distances. That may be quite a shocking eye opener. They average distance differences per class are  :o
Sporty type cars like say a BMW 3 series stop some 30% shorter than compact EVs/hybrids. Those are about on par with light trucks and vans.
Comparing with dedicated sports cars it gets jaw dropping and that is not really about the brákes but mainly about the rubber. Of course there are more factors but the tables read almost as a grip listing.

So, imo, extra grip does add safety. The only caveat being the operating temp window. This is @Nvy why the 888s are not on my list.


Dev


Quote from: Nvy on September 26, 2022, 06:17What about toyo 888 square 205?
Just a heads up. The Toyo 888 are notorious for heat cycling out early from this class of tire. There were a few owners that used these tires with this finding. 
Actually most extreme performance heat cycle out much faster that you are likely to have plenty of tread left on the tire by the time they are spent.

 This is not really an issue because this class of tire was primarily designed for race applications where they meet street car class rules so they can compete. This is very much a gray area of being cheat tires where they still qualify for the street but become expended early so if you have a deep wallet you can keep replacing tires.
For a street application they can be very inconsistent based on temperature and they will decay quickly where they will be equivalent to the summer category of tires and given enough time they will drop off the chart in terms of grip where they will be dangerous. So unless you keep changing tires there is not much value in it.
I learned the hard way when I lost control with treating extreme tires like summer performance thinking that I haven't heat cycled them out.



Dev

Quote from: Petrus on September 26, 2022, 08:13The cyclist you could have stopped for may differ in opinion.


 Not to criticize as there is plenty of fault in the way I drive but if this is your concern you are driving way too fast if you cant slow down fast enough for a cyclist and it shouldn't be dependent on location. If you are placing all of your bets on the grip of the tires it might not pan out the way you predict considering stoping distance also depend on the brakes ability to take advantage of that extra grip without fading. 
The roads I travel are full of cyclists and blind spots over hills where this can be an issue but on the whole even if I were speeding I have plenty of distance to slow down so it would never be a factor even if I was in a commuter car with all season tires.
 Unfortunately it is not the greatest time to be a cyclist in my country because of distracted driving and SADS.
 

Petrus

#9
The tarmac at your region @Dev, how is that?
Over here it is wáy different from UK, Netherlands. The % of gravel/sand is significantly higher vs more bitumen up north.
The reason is obvious; to prevent it running down the slopes on a hot day. It also results way more brittle (prone to break up in winter) and less grippy. When it wears, it is practically polished pebbles you are driving on. Now add grime on bus routes, at busy crossings  with ´STOP´ sign, at traffic lights and you get the equivalent of black ice.
Right, that is when dry. When it starts raining after a long dry spell, I try avoid going on the road. The very first shower will see edges of foam! from water and grime emulsifying.
Never mind the Sahara dust we had drizzling on everything including roads  :o
Anyway, best think of the 300 sunny days  8)


I am quite aware of heat cycling the tyre. For some 6 months of the year I get them up to 50 - 60 degrees  C. on most longer rides.
Even on a sunny winter afternoon I get them as a rule around 40.

Here is a nice page treating with Yokohama sports rubber working temps:

https://www.adamsandpage.co.uk/motorsport-racing-tyres/yokohama-racing-tyres

My use should ´warrant´ the A052 as far as operating temp. goes but they are a ´bit´ pricey to cycle out in a summer.
But ´Nothing rewards your passion for extreme grip and high speeds like the all-new ADVAN A052 from Yokohama.´  - Yokohama  ;)  ;D

The AD08R was an imo none too bad compromise.
The RS version may be ´better´ compromise still. That is what between the lines is the motivation of the development.

Have requests for quotes out. 
In 195/50 for the fronts btw.

The cyclist Dev is just an example for the unforseen. It can also be a sheep dashing from the verge. In no real world can you drive slow enough for the unexpected.
The good old rule of not outdriving the distance you can oversee and stop within does not apply to things you should not reasonably expect.
In a built up area or with cars parked at the side it is totally different from a mountain rd. with nóóó buildings near the road. In the first instance one should drive as if a kid could run after a ball any moment.  The latter ... not so much yet I háve had a cyclist coming ´out of the bushes´  descending from a narrow gravel footpath onto the road. Swerve while braking is the only possible reflex and max traction your saviour. Much the same is game crossing an unlit country rd at night. Even if you sort of expect that, it is just a matter of chance how close to the car the deer jumps into your lit beam.
Where I used to live in the Netherlands there was a downright hilárious seire of incidents with roe deer on the local secondary rd. : The local police received a nightly call about  a car in a ditch because it had hit a deer crossing.
They patrol car, definitely ware of the risk, went to assist and.... same thing a few hundred meters earlier.
They called it in too. Collegues went out now doúbly warned and.... you get the gist.
No injuries to it was just funny but it does go to show.
I have had near misses in that region too.

On the motorbike it is worse still as you yourself are the crumple zone. I have been very lucky. Hit a cat, a largish dog; no fall. Was hit by a bird twice. A small one in the goggles and a coot in the chest. Neither took me out but were close enough.
None of these four incidents were speeding yet only in the case of the dog I had time to react; momentarily brake and then pull the front.
Sh@t happens Dev and the more grip you have the less luck you need.


Dev

#10
Fortunately the roads in my area are some of the best I have seen where maintenance is key. I did not realize how good they were until I traveled to other areas of the country like Detroit and Seattle. Even if your roads are not ideal it would just mean being aware and diving at a speed that is safe especially for others. That is the way I see it as I have to be aware that I have to slow down much more than my commuter car when it rains because the suspension is tighter which can easily make the car tail spin going on an off ramp. Situation awareness based on the compromises you have made to your car is paramount. Not you in particular but I often see people only factor the upsides of tires based on reviews and charts but they ignore the reality of driving with tires that have practical downsides. Also I have noticed tires that are popular on one platform can perform poorly on another and this could be due to a multitude of engineering factors that are inherent to each car. 




MikeBoo

Peoples preferences of tyres seems to be a very personal choice as well all have our own preferences, requirements, previous experiences as well as who's advice we take on board (whether that's a company's marketing, a 3rd review, friends, etc).

However a couple of things that some people forget or aren't aware of is that the same make/model of tyre can have a different compound and/or structure depending on it's size.
Also some tyres are designed specifically for a specific makes or even down to a specific model of car. I know some on here will say this is all about marketing, but consider that Porsche sell the 911 992 with tyres made by Michelin specifically for that model of car and the front & rear of which are different sizes also have a different design and also have different compounds on different sections of the tyres. One of the reasons they give for this difference is that the rear of the car is a lot heavier than the front and therefore the sidewalls need to be stiffer.

This thread comes just after I bought 4 new tyres this weekend for the family car in readiness for the MOT next month. Even though they were still considered legal, two tyres had obvious damage from misalignment (severe outside edge wear) each with 2.4 to 4mm of tread, the other pair had just under 3mm with cracking/crazing on the outside edge by the tread blocks.
I chose the replacements initially based on being a well known mid range make, a recent tyre model, rain rating of >=B, Fuel>=C & a noise rating <=71dB. Then compared prices online and went with the best price I could get fitted locally as there's no point driving 20+ miles to save a small amount of money.
My wallet is now just over £440 lighter  :(
2001 Toyota Liquid Silver (1D0) with hard top & original soft top.
Yokohama AD08RS all round.
Replacement manifold, BC coil overs,
Whiteline anti roll bars front & rear & Ultra Racing front strut brace.
Location = East Hampshire, UK

Petrus

Quote from: Dev on September 26, 2022, 16:47Also I have noticed tires that are popular on one platform can perform poorly on another and this could be due to a multitude of engineering factors that are inherent to each car. 


I go back almost as far @Joesson and already had a drivers license when radial tyres were not standard fitment yet. I líved the engineering change of rubbers incorporated in the suspension to adapt to these new tyres.

The akin development of motorcycles was a bit more challenging but WOW did it change grip, stability and comfort.

Just the other weekend at the classic meet drove an early mini. Just a spin through the village but what horror. It was ´rallyfied´ with too wide too large diameter mini-lite lookalikes shod with 45 section radials. Nice 20th c. rubbah, delightful little sixties previous c. car, horrible mismatch.

As @Ardent mentioned though development can throw a nasty spanner in the wheels. It can be quite a challenge to find the suitable tyre for a pre-modern car. Our MR2 is a case in point. The OEM tyre is no longer produced and choice of alternatives not as wide as it was with basically none with as stiff sidewalls. And that for a millennium car!!
Even Yokohama may not bother to manufacture its new AD09 in 15 or 16 inch.

For 20th c. cars a slightly sub ideal tyre type is most likely to be more than compensated by better modern rubber compounds offering grip not available then. Which btw has a B side to it as well  ;)  Better drive within the design limits not those of the modern rubber  ;D


Petrus

Quote from: MikeBoo on September 26, 2022, 17:16However a couple of things that some people forget or aren't aware of is that the same make/model of tyre can have a different compound and/or structure depending on it's size.

It can be quite surprising that with apparently no rime nor reason in the same type of tyre yes.
Depending on the depth of one´s OCD is can be worth the effort to dig through specs tables.
Sadly the tyre ´pro´ in tyre shops not always is the one in the know.

MikeBoo

Quote from: Petrus on September 26, 2022, 17:49It can be quite surprising that with apparently no rime nor reason in the same type of tyre yes.
Depending on the depth of one´s OCD is can be worth the effort to dig through specs tables.
Sadly the tyre ´pro´ in tyre shops not always is the one in the know.
My takeaway here was that by fitting different width/profile tyres to what had been fitted as standard, one cannot assume that the driving characteristics will always change as expected. Also just because someone else praises a particular tyre (of a different size) on one car doesn't always mean that they will exhibit the same characteristics on another make/model of car.

Also I agree that the tyre 'pro' is rarely knowledgeable about tyres or the fitting there of; as it seems that they couldn't even differentiate the front & rear wheel nuts on my car.
2001 Toyota Liquid Silver (1D0) with hard top & original soft top.
Yokohama AD08RS all round.
Replacement manifold, BC coil overs,
Whiteline anti roll bars front & rear & Ultra Racing front strut brace.
Location = East Hampshire, UK

Dev

Quote from: MikeBoo on September 26, 2022, 17:16Also some tyres are designed specifically for a specific makes or even down to a specific model of car.

This is very true and proven to be true. You can have the same identical tire in the same size sold at a tire shop and it can be different then the factory tires that can only be purchased at the dealer.

There is a marking on the tires that differentiate the factory tires that was made by request by the car manufactures to match the performance of the specific car.
They say that even if you cannot get the factory specific tires the next best thing is to buy the closely identical tires. 
I really do not know how much actual difference can be appreciated but it speaks volumes if the manufactures of both the tire and car are going though the trouble and expense of making tailored made tires.

  What I found works is to try to match closer to OEM tires especially when most do not have means for a bases of compassion. I believe the engineers are as correct as tuning a musical instrument rather than personal preference. This means stiff sidewalls to match the suspension which is rare these days because of plus sizing for larger wheels. 


Joesson

Quote from: MikeBoo on September 26, 2022, 17:16Peoples preferences of tyres seems to be a very personal choice as well all have our own preferences, requirements, previous experiences as well as who's advice we take on board (whether that's a company's marketing, a 3rd review, friends, etc).

However a couple of things that some people forget or aren't aware of is that the same make/model of tyre can have a different compound and/or structure depending on it's size.
Also some tyres are designed specifically for a specific makes or even down to a specific model of car. I know some on here will say this is all about marketing, but consider that Porsche sell the 911 992 with tyres made by Michelin specifically for that model of car and the front & rear of which are different sizes also have a different design and also have different compounds on different sections of the tyres. One of the reasons they give for this difference is that the rear of the car is a lot heavier than the front and therefore the sidewalls need to be stiffer.

This thread comes just after I bought 4 new tyres this weekend for the family car in readiness for the MOT next month. Even though they were still considered legal, two tyres had obvious damage from misalignment (severe outside edge wear) each with 2.4 to 4mm of tread, the other pair had just under 3mm with cracking/crazing on the outside edge by the tread blocks.
I chose the replacements initially based on being a well known mid range make, a recent tyre model, rain rating of >=B, Fuel>=C & a noise rating <=71dB. Then compared prices online and went with the best price I could get fitted locally as there's no point driving 20+ miles to save a small amount of money.
My wallet is now just over £440 lighter  :(

I can only like thàt post until the last line!

Joesson

In reference to the above mentions of stopping distances and avoiding cyclists. That is not a hypothetical situation.
A friend, who was a private pilot, had a VX 220 as his other weekend toy, as well as motor cycles with very well used side walls had undertaken a charity cycle ride from John O'Groats to Lands End ( having previously done the opposite journey).
The charity was Air Ambulance Because I'm likely to need them at some point was his reasoning.
He got as far as Exeter before he disappeared from the tracker screen.
A passing car had clipped him, he fell in front of a following car that didn't avoid him, with fatal result.

Petrus

Quote from: Joesson on September 26, 2022, 19:06In reference to the above mentions of stopping distances and avoiding cyclists. That is not a hypothetical situation.
A friend, who was a private pilot, had a VX 220 as his other weekend toy, as well as motor cycles with very well used side walls had undertaken a charity cycle ride from John O'Groats to Lands End ( having previously done the opposite journey).
The charity was Air Ambulance Because I'm likely to need them at some point was his reasoning.
He got as far as Exeter before he disappeared from the tracker screen.
A passing car had clipped him, he fell in front of a following car that didn't avoid him, with fatal result.

Uffff. I am very sorry to read that; my condolances.

Been with two and three wheels since I could walk and have experienced too many close shaves to count. Only minor bumps. Give all a wíde birth = no overtaking cyclists/mopeds with oncoming traffic p.e.

A second observation also comes from two wheels; motorbikes: Keeping your distance from the vehicle in front is só important. The clipped cyclist is an ultimate bad as example but more common is the car ahead passing over something which you thus can only see when it appears from underneath.
Same thing lorries.  You can see even less, i.e. nothing ahead of those ánd they pass over bulkier objects.
Obviously a survival thing on a motorbike but still very much important in a car. See the above.

One of my main worries is a cyclist or motorcyclist barrelling down around a blind corner on a mountain rd.  For one they need surprising width and secondly they cannot swiftly change course. It makes me keep to the utmost outer edge as a second nature. The rubber limits how short you can stop.

You can by its nature not foresee the unforeseen, but you should not fail to anticipate the potential risks you cán literally (fore)see.
Again I want to point to the book The Art and Technique of Driving, 1965 by Pat Moss and Erik Carlsson. It very heavily goes into and explains anticipation. Much of what they write is the now sadly lost art of applied common sense in traffic.

Again a decennia on two/three wheels thing is a daily normal thing to notice that I anticipate on something one or more cars ahead and observe how just in time thóse respond.
That make you aware that you yourself on a bike or in a low car will be reacted to that late as well  :o   Safer to assume that they will not see you, not respect your right of way.

Ardent

Quote from: Dev on September 26, 2022, 18:20What I found works is to try to match closer to OEM tires
That is my guide. I go for a close to OEM as I can get.


Dev

#20
Quote from: Ardent on September 26, 2022, 22:40That is my guide. I go for a close to OEM as I can get.



 Thats what I found after many tire changes. Although I do not run same size tires as OEM due to my wheels I have the same class of tire, brand and stiff sidewalls that makes it feel like I remember when I first bought the car. It is as if the timing of the suspension when going over bumps on irregular roads is far more responsive which makes sense since the tires are part of the suspension system and eliminating compliance from the tires makes the suspension work well to transfer instant feel for the driver especially when you load up the suspension around corners and even braking.


Ardent

Sidewall stiffness the missing parameter of info on a sidewall.
I have the correct sizes, load and speed ratings. But the composition/construction of the sidewall is not OEM.

Perhaps it comes down to choosing your compromise. Like services, Fast - cheap - high quality. Choose any two.

Petrus

Quote from: Ardent on September 26, 2022, 23:25Sidewall stiffness the missing parameter of info on a sidewall.

Ever so true.
Our MR2 is especially affected as the OEM ones were Bridgestone RE040 or Yokohama A043, neither of which are available and both were quite stiff.
More modern tyres tend to be more flexible. Even the modern road legal racing A052 is quite a lot softer!
The racing A048 was and now the A050 is stiffer and even comes in the correct size/load index but.... not road legal.

An indirect clue concerning sidewall stiffness is the optimum negative camber range suggested by the manufacturer for track use. The more negative camber suggested, the softer.  The old A048 was -1 to -2,5 whereas the new A052 is -3,5 to -4,0.
This is a clear pointer to the latter behaving very differently from the stiffness the ZZW30 engineers intended.
For regular road tyres such info is sadly lacking.

Dev

Performance tires two decades ago had stiff sidewalls. The reason why we have soft side walls now is primarily for plus sizing as wheels grew in diameter with lower profiles and the consumer was complaining about road comfort and so they could avoid damage. The reason why we could not get a stiff version for our 15 or 16 inch wheels is primarily because tire manufacturing became standardized where the compromise would be overlooked by 90% of drivers. Our cars are very reactive and sensitive to change and therefore we can certainly appreciate the difference.


Petrus

#24
And the mismatch of tyre construction/properties with what the car´s designers worked with is thus something imposed on the owners, not a choice. Even if you would somehow deduct which tyres have softer sidewalls, you still are limited by what is (no longer) availeble.

Right. Have the quotes in and the soppy sidewall issue apart AD08RS it is. The A052 is just silly money.
Those too have increased in price since year 0. Beejeezus. 440 pound sterling does not cover it. *
Opting to buy just down the road. Great service, immediate attention, they do what Í want and prices are same as adding mounting/balancing to the cheapest internet offer with the added advantage of guarantee at 1 km.
Next is when, the resident female being unconvinced that there can be other reasons to replace perfectly ok looking tyres.
I cán do whatever I want but there is rather a difference between head wind and tail wind.

* p.s. just back from shopping.  Relative to the cost of thát the tyres are actually quite cheap and the price hike is léss than the cost of fuels and drop in exchange rate. 488€ incl. all is only 10% up since spring 2019.
And relative to what people are paying for utility bills... The price hikes for some since year 0 would pay for the sports rubber in a single winter month!!!