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Weird tire behavior


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#1 MattPete

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Posted 21 July 2022 - 21:30

One of the discussions about handling in one of the F1 threads gave me flashbacks to a weird set of tires I had years ago on an Infiniti G20 (Nissan Primera for the Brits) back in 2002.

 

Up to that point I had had several different tires on the car: 195/60-14 Michelin XGT (stock tire), 205/50-15 Dunlop D40m2 (BBS wheels), some cheap Hankooks that replaced the Dunlops, and a set of Pirelli 190p snow tires on the stock wheels.  None of them acted funny in any manner, and all performed as expected.

 

I needed a new set of tires, and since I was moving to less snowy climate, and I wanted to save some money, I decided to replace the snow tires on stock wheels with touring/performance tires.  I don't remember the exact model, but it was a budget tire from Yokohama.

 

As soon as I left the shop, I noticed they had a peculiar behavior.  At initial turn-in (imagine navigating a 90° turn along the access roads of a shopping center at 20 mph) nothing happened.  I turned the wheel, and the car still went straight.  In fact, I'm pretty sure I tried to correct this by turning the wheel even more. Then, after a delay (half second?) the car would turn.  It was almost like there was understeer, but it wasn't technically understeer, as there was no skidding.

 

But that's just the front tires. The rear tires had basically the same behavior as the front tires: the front of the car is now starting to turn, but the rear tires are wanting to continue to go straight, in the direction the rear wheels had been pointing. Which meant it felt like oversteer.  Then, after a half second (?) the rear tires would decide to align themselves with their wheels, and the feeling of oversteer would go away.

 

So initial understeer followed by oversteer, at 20 mph in a parking lot, all at levels well below the tires' friction circle.  That behavior remained for the entire time I owned those tires. 

 

I eventually had to adjust my driving style to the tires (it was probably the MCL36 thread that gave me flashbacks to these tires), but after 4 months of weird driving, I replaced them with a new set of Michelin XGTs, and everything was back to normal.  No other car or minivan I've driven, before or since, had that peculiar behavior.

 

Whatever was going on with those tires, my hunch is that it had something to do with sidewall stiffness and slip angle, but I'm kinda shooting in the dark. Any ideas?



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#2 Greg Locock

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Posted 22 July 2022 - 00:24

Half a second is probably just a fear induced estimate. The topic is called tire relaxation length, and as you say is related to the ratio of sidewall lateral (or perhaps twisting) stiffness to lateral cornering stiffness.

 

It does vary quite a lot depending on tire construction, at 20 mph it'd be around 50 ms delay at most, not 500. 

 

So, all very odd.



#3 404KF2

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Posted 22 July 2022 - 03:54

Tread squirm can be awful, but usually in cheap snow tires. I would not have expected that from Yokohama. Maybe they forgot to put the radial casings in the mold  :confused:



#4 GregThomas

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Posted 22 July 2022 - 04:00

It can also have a bit to do with tyre construction. We saw a good example of this back when we ran genuine production bike racing in NZ.  Metzelers gave the best grip at the limit - but you had to get used to the delayed response to turning input. Very similar to what's described above. Pretty well every tyre for those bikes had the same profiles so should have steered the same but Dunlops were probably the stiffest carcase and Metzeler the most flexible.

First rides on Metzelers were often a bit unnerving.



#5 Catalina Park

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Posted 22 July 2022 - 09:34

A friend had a Holden Commodore VP SS IRS etc in the early 2000s. It had a pair of Yokohamas on one end and Bridgestones on the other end and it was pretty much undrivable with the rear end wandering.
I swapped the tyres front to back and it was transformed (as much as a Commodore could be).
I assumed it was the tyre construction not liking the amount of rear camber and a difference in slip angles between brands.

I wanted to try them side to side just for comparison but was overruled.



#6 MattPete

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Posted 22 July 2022 - 10:40

Half a second is probably just a fear induced estimate. The topic is called tire relaxation length, and as you say is related to the ratio of sidewall lateral (or perhaps twisting) stiffness to lateral cornering stiffness.

 

It does vary quite a lot depending on tire construction, at 20 mph it'd be around 50 ms delay at most, not 500. 

 

So, all very odd.

 

Yeah, 500 ms was probably a fear-induced overestimation, but it felt like an eternity.



#7 MattPete

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Posted 22 July 2022 - 11:13

Tread squirm can be awful, but usually in cheap snow tires. I would not have expected that from Yokohama. Maybe they forgot to put the radial casings in the mold  :confused:

 

I remember it had the same tread pattern as the Avid T4, but it was a cheaper model with a different name (and presumably different construction).

 

yo_avid_t4_l.jpg?1539071212

 

 

 

I wish I could remember the model #.  I do remember that it had the same tread pattern as the Avid T4.  Ironically, these were replacing snow tires, albeit Pirellii 190Ps, which I bought because they were supposed to be pretty decent in the dry (and they were).



#8 Sterzo

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Posted 22 July 2022 - 11:31

Fitted Yokohamas to a company Vauxhall Cavalier back in the nineties. Terrified myself driving out of the car park, turning the wheel with little effect. Never experienced anything like it. Were I a professional racing driver I'd have said "No grip for sure." As it was I said: "I want my Mum."



#9 Bikr7549

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Posted 22 July 2022 - 19:36

I had the opposite reaction once, replaced some old Dunlops with Conti's and for the first few days the feeling of a much quicker reaction on turn in was simply amazing. Then of course I got used to it and it became normal.


Edited by Bikr7549, 22 July 2022 - 19:36.


#10 milestone 11

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Posted 22 July 2022 - 20:52

I bought a set of Yokohama A-008 asymmetric for a Montecarlo, they were horrendous. I dumped them after just a few weeks. They worked better if the car was pushed but no good for a road car, you'd spend more time in court.

#11 Magoo

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Posted 23 July 2022 - 00:09

Reminds me a bit of when the USA was (begrudgingly) adapting to radial tires and many car owners still had their old bias-ply snow tires for winter. 



#12 MattPete

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Posted 23 July 2022 - 15:58

Fitted Yokohamas to a company Vauxhall Cavalier back in the nineties. 

 

If it was the late-90s, maybe it was the same model of tire that spooked me!



#13 Bloggsworth

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Posted 23 July 2022 - 16:04

One of the discussions about handling in one of the F1 threads gave me flashbacks to a weird set of tires I had years ago on an Infiniti G20 (Nissan Primera for the Brits) back in 2002.

 

Up to that point I had had several different tires on the car: 195/60-14 Michelin XGT (stock tire), 205/50-15 Dunlop D40m2 (BBS wheels), some cheap Hankooks that replaced the Dunlops, and a set of Pirelli 190p snow tires on the stock wheels.  None of them acted funny in any manner, and all performed as expected.

 

I needed a new set of tires, and since I was moving to less snowy climate, and I wanted to save some money, I decided to replace the snow tires on stock wheels with touring/performance tires.  I don't remember the exact model, but it was a budget tire from Yokohama.

 

As soon as I left the shop, I noticed they had a peculiar behavior.  At initial turn-in (imagine navigating a 90° turn along the access roads of a shopping center at 20 mph) nothing happened.  I turned the wheel, and the car still went straight.  In fact, I'm pretty sure I tried to correct this by turning the wheel even more. Then, after a delay (half second?) the car would turn.  It was almost like there was understeer, but it wasn't technically understeer, as there was no skidding.

 

But that's just the front tires. The rear tires had basically the same behavior as the front tires: the front of the car is now starting to turn, but the rear tires are wanting to continue to go straight, in the direction the rear wheels had been pointing. Which meant it felt like oversteer.  Then, after a half second (?) the rear tires would decide to align themselves with their wheels, and the feeling of oversteer would go away.

 

So initial understeer followed by oversteer, at 20 mph in a parking lot, all at levels well below the tires' friction circle.  That behavior remained for the entire time I owned those tires. 

 

I eventually had to adjust my driving style to the tires (it was probably the MCL36 thread that gave me flashbacks to these tires), but after 4 months of weird driving, I replaced them with a new set of Michelin XGTs, and everything was back to normal.  No other car or minivan I've driven, before or since, had that peculiar behavior.

 

Whatever was going on with those tires, my hunch is that it had something to do with sidewall stiffness and slip angle, but I'm kinda shooting in the dark. Any ideas?

Are you sure you weren't driving a shopping trolley? Sounds like faulty set of tyres to me.



#14 Fat Boy

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Posted 24 July 2022 - 16:36

I bought a set of Yokohama A-008 asymmetric for a Montecarlo, they were horrendous. I dumped them after just a few weeks. They worked better if the car was pushed but no good for a road car, you'd spend more time in court.

A008's were awesome. If you didn't like them, that's on you and your car. That tire stuck like sh!t to a blanket and driving them was more fun than a bucket of eels. It was a semi-slick, so it would get dicey in the wet, but that should have been pretty bloody obvious from the first glance. Yokohama's present sticky tire is the A052. It doesn't last long, but it's a lot of fun while it's around.



#15 JacnGille

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Posted 24 July 2022 - 17:26

A008's were awesome. If you didn't like them, that's on you and your car. That tire stuck like sh!t to a blanket and driving them was more fun than a bucket of eels. It was a semi-slick, so it would get dicey in the wet, but that should have been pretty bloody obvious from the first glance. Yokohama's present sticky tire is the A052. It doesn't last long, but it's a lot of fun while it's around.

A008 were original tires on my '85(?) Doge Colt Turbo. Great tires for me.



#16 Greg Locock

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Posted 24 July 2022 - 22:10

Here's a completely unreliable database of tire reviews, but at least it is a start. https://www.tyrerevi.../Tyre/Yokohama/


Edited by Greg Locock, 24 July 2022 - 22:11.


#17 Fat Boy

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Posted 24 July 2022 - 22:58

Here's a completely unreliable database of tire reviews, but at least it is a start. https://www.tyrerevi.../Tyre/Yokohama/

Their A052 review is bang on. The A008 is a tire from the 90's that only the geekiest of geeks would remember. It was probably 5 tire generations ago. It competed with the Goodyear GS-CS and BFG R-compounds of the day.



#18 NRoshier

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Posted 30 July 2022 - 13:02

AO52's are popular with local enthusiast cars for road and track use. AO50's are faster and more track oriented. The best report not included in the reviews is that the grip is consistent through the life of the tyre. Previous A)48's were notorious for going hard before 50% of tread wear - then they'd never wear out - or grip.



#19 GreenMachine

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Posted 30 July 2022 - 13:29

Long term AO50 user (medium compound).  Neil has nailed it, they last well, retain high grip levels until they run out of rubber.  Expensive, but very good value, probably the go-to tyre for anyone chasing lap time if you can stand the up-front cost.



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#20 MattPete

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Posted 30 July 2022 - 16:53

Their A052 review is bang on. The A008 is a tire from the 90's that only the geekiest of geeks would remember. It was probably 5 tire generations ago. It competed with the Goodyear GS-CS and BFG R-compounds of the day.

 

Dude, the A008 is from the 80s!  I think it was the stock tire on the Mitsubishi Starion (which I thought looked completely badass back in the day). I think the A008s were pretty deadly in the rain.

 

The autocrossers I knew used to run A008R or Hoosier Autocrossers.



#21 MattPete

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Posted 30 July 2022 - 16:55

Around 1990, I had a set of AVS Intermediates.  Fantastic tires.  That's why I was shocked by spooky tires I got 10 years later.

 

Granted, the AVS Intermediates were a premium tire and the spooky tires were budget tires, but still...



#22 Fat Boy

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Posted 10 August 2022 - 16:17

Around 1990, I had a set of AVS Intermediates.  Fantastic tires.  That's why I was shocked by spooky tires I got 10 years later.

 

Granted, the AVS Intermediates were a premium tire and the spooky tires were budget tires, but still...

You know, it's entirely possible that you got a bad tire in there somewhere. If you just had one tire in the mix which slipped through QC with a bad construction, it will throw off the handling balance of the whole lot.