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Hankook RS4 Flat Spot?


squid08
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We ran the RS4 this past weekend at a 24 hour race. Developed what I believe is a flat spot from a brief locked tire pretty early on; vibrations made worse at higher speeds, the issue was more prominent when tires were cold (long yellows). Naturally, every time a driver would threshold brake the flat spot was found and made worse as the weekend went on.

 

Did you guys have issues with flat spots from locked tires on the RS3? We did not seem to have this issue with the Falken 615K with some pretty big lockups with no real noticeable effect.

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We noticed it on the rivals and rs3.  They are not loud tires so you can flay spot without much indication.

 

How did they do?  Last the 24 hours?  How was grip?  What car, hp, and weight?  Heat cycled first?

 

Anything else unusual to report?

 

Thanks!

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1 hour ago, squid08 said:

 

Did you guys have issues with flat spots from locked tires on the RS3? We did not seem to have this issue with the Falken 615K with some pretty big lockups with no real noticeable effect.

 

Agree, my team has made numerous attempts to flat spot our Falkens, thankfully we have only been successful once or twice.  

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7 minutes ago, Ron_e said:

 

Agree, my team has made numerous attempts to flat spot our Falkens, thankfully we have only been successful once or twice.  

Do ya'll hire rental drivers???

 

I can flat spot an Azeni in a heartbeat. ... have you seem my rev limiter video? :)

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3 hours ago, wvumtnbkr said:

We noticed it on the rivals and rs3.  They are not loud tires so you can flay spot without much indication.

 

How did they do?  Last the 24 hours?  How was grip?  What car, hp, and weight?  Heat cycled first?

 

Anything else unusual to report?

 

Thanks!

 

Thanks for that feedback. Unfortunate as our drivers sometimes have a large variation of skillset.

 

The tires were good, but I wouldn't say it was world changing. More grip than the 615k but we did go from 205 to 225, so not sure how much is attributed to width. Under braking was the most noticeable gain. We started running the tires around 34psi hot and went down to ~28psi hot at the end, didn't have a great conclusion on what the best pressure to run was. There was a bit of squirmyness under threshold braking around 32psi, and we went down to the 28-30 range as the track cooled overnight.

 

Lasted the full 24 and probably has another 8 hours in them which is fantastic; our drivers were pushing the car pretty hard.

 

This was in a miata, didn't do any preparation to the tires, did a practice session for an hour just before race start. Noticed in practice that they felt a bit greasy but it went away. It wasn't really possible to overdrive the tire, after a bit of sliding they still didn't grease up like the 615 is known for.

 

Sidewalls felt much softer than the 615, there was a bit more side to side mushyness in the car; we went from 205 on 7 inch rim to 225 on 7inch rim, I think some of the soft floaty feel might be from the rim and tire size combo.

 

My biggest complaint relative to the 615k is the lack of feedback audibly on the RS4. It also seemed like it was a bit less forgiving/had a steeper limit drop off curve. Still very controllable. 

 

For reference, our best time was a low 2:17 at buttonwillow  cw1 ( starmazda ) in a 1.6 miata . Unsure what spec cars do around that config on their stickier tires.

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10 minutes ago, squid08 said:

 

Thanks for that feedback. Unfortunate as our drivers sometimes have a large variation of skillset.

 

The tires were good, but I wouldn't say it was world changing. More grip than the 615k but we did go from 205 to 225, so not sure how much is attributed to width. Under braking was the most noticeable gain. We started running the tires around 34psi hot and went down to ~28psi hot at the end, didn't have a great conclusion on what the best pressure to run was. There was a bit of squirmyness under threshold braking around 32psi, and we went down to the 28-30 range as the track cooled overnight.

 

Lasted the full 24 and probably has another 8 hours in them which is fantastic; our drivers were pushing the car pretty hard.

 

This was in a miata, didn't do any preparation to the tires, did a practice session for an hour just before race start. Noticed in practice that they felt a bit greasy but it went away. It wasn't really possible to overdrive the tire, after a bit of sliding they still didn't grease up like the 615 is known for.

 

Sidewalls felt much softer than the 615, there was a bit more side to side mushyness in the car; we went from 205 on 7 inch rim to 225 on 7inch rim, I think some of the soft floaty feel might be from the rim and tire size combo.

 

My biggest complaint relative to the 615k is the lack of feedback audibly on the RS4. It also seemed like it was a bit less forgiving/had a steeper limit drop off curve. Still very controllable. 

 

For reference, our best time was a low 2:17 at buttonwillow  cw1 ( starmazda ) in a 1.6 miata . Unsure what spec cars do around that config on their stickier tires.

So, it sounds to me like if anything Hankook decided to increase the wearability of the tire. I'm a little concerned about your impression of the traction drop-off.

The RS3s didn't have a traction issue in my opinion.  They definitely didn't get as greasy as an Azeni but I could tell when they were getting hot.

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11 minutes ago, dogtired said:

So, it sounds to me like if anything Hankook decided to increase the wearability of the tire. I'm a little concerned about your impression of the traction drop-off.

The RS3s didn't have a traction issue in my opinion.  They definitely didn't get as greasy as an Azeni but I could tell when they were getting hot.

You have to remember that I haven't driven this car on RS3's. There was a BMW 2002 running RS4's as well, after the race the driver told me that he didn't really notice a difference from the RS3's.

 

My biggest concern is how the flat spot came about and if it is more or less prone to happen with this tire.

 

Would love to hear the feedback from others when they test this tire finally.

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Couple thoughts come to mind.  The harder the tire, the harder it will be to flat spot.  

What brakes are you running?  Our Miata is reasonably hard to lock up the wheels.  That being said, we've done it and flat spotted tires.  

 

I think you would like the 225 much better it you had them on 9in wide wheels.  I think everyting from turn in to braking would improve.  

 

I'm encouraged by the longevity you saw with the RS4  thanks for reporting on them

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4 hours ago, JDChristianson said:

Couple thoughts come to mind.  The harder the tire, the harder it will be to flat spot.  

What brakes are you running?  Our Miata is reasonably hard to lock up the wheels.  That being said, we've done it and flat spotted tires.  

 

I think you would like the 225 much better it you had them on 9in wide wheels.  I think everyting from turn in to braking would improve.  

 

I'm encouraged by the longevity you saw with the RS4  thanks for reporting on them

Good thought on the wheel width, might have to buy wider rims. Anyone in the bay area interested in 2 sets of Advanti Storm S1's? 15x7

 

We are running Raybestos ST-43 on stock 1.6 brakes. They have way more bite than the tires will hold (very easy to lock), but if you get it right we can out-brake most cars. After running the pads at the Feb Chump Sonoma race and this 24hr we still have a bit more than 1/4 pad left all around.

 

What brake pad are you running?

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We have been using Hawk DTC60 in front and DTC 30 in the rear.  I really didn't like the feel of the Raybestos pads, and others on the team didn't care for them either.  They weren't as fussy as me but....    The Hawks don't last as long for sure but they work ok.  We had no trouble getting 16 hours out of them at Vegas for example.  The feel and modulation on them is great.  In my opinon any how.  
 

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